Below is a code sample containing drawing methods for drawing check boxes or any control type in a grid based layout similar to the SelectionGrid.

 
    using System;

    using UnityEngine;

    public class ControlGrid
    {
        /// <summary>
        /// Draw a grid of check boxes similar to SelectionGrid.
        /// </summary>
        /// <param name="checkedValues">Specifies the checked values of the check boxes.</param>
        /// <param name="text">The content for each individual check box.</param>
        /// <param name="columns">The number of columns in the grid.</param>
        /// <param name="style">The style to be applied to each check box.</param>
        /// <param name="options">Specifies layout options to be applied to each check box.</param>
        /// <returns>Returns the checked state for each check box.</returns>
        /// <remarks><p>Check boxes are drawn top to bottom, left to right.</p>  </remarks>
        /// <exception cref="IndexOutOfRangeException">Can occur if the size of the array is too small.</exception>
        public static bool[] DrawCheckBoxGrid(bool[] checkedValues, string[] text, int columns, GUIStyle style, params GUILayoutOption[] options)
        {
            // convert string content into gui content
            var content = new GUIContent[text.Length];
            for (var i = 0; i < content.Length; i++)
            {
                content[i] = new GUIContent(text[i]);
            }
            return DrawCheckBoxGrid(checkedValues, content, columns, style, options);
        }

        /// <summary>
        /// Draw a grid of check boxes similar to SelectionGrid.
        /// </summary>
        /// <param name="checkedValues">Specifies the checked values of the check boxes.</param>
        /// <param name="textures">The content for each individual check box.</param>
        /// <param name="columns">The number of columns in the grid.</param>
        /// <param name="style">The style to be applied to each check box.</param>
        /// <param name="options">Specifies layout options to be applied to each check box.</param>
        /// <returns>Returns the checked state for each check box.</returns>
        /// <remarks><p>Check boxes are drawn top to bottom, left to right.</p>  </remarks>
        /// <exception cref="IndexOutOfRangeException">Can occur if the size of the array is too small.</exception>
        public static bool[] DrawCheckBoxGrid(bool[] checkedValues, Texture2D[] textures, int columns, GUIStyle style, params GUILayoutOption[] options)
        {
            // convert texture content into gui content
            var content = new GUIContent[textures.Length];
            for (var i = 0; i < content.Length; i++)
            {
                content[i] = new GUIContent(string.Empty, textures[i]);
            }
            return DrawCheckBoxGrid(checkedValues, content, columns, style, options);
        }

        /// <summary>
        /// Draw a grid of check boxes similar to SelectionGrid.
        /// </summary>
        /// <param name="checkedValues">Specifies the checked values of the check boxes.</param>
        /// <param name="content">The content for each individual check box.</param>
        /// <param name="columns">The number of columns in the grid.</param>
        /// <param name="style">The style to be applied to each check box.</param>
        /// <param name="options">Specifies layout options to be applied to each check box.</param>
        /// <returns>Returns the checked state for each check box.</returns>
        /// <remarks><p>Check boxes are drawn top to bottom, left to right.</p>  </remarks>
        /// <exception cref="IndexOutOfRangeException">Can occur if the size of the array is too small.</exception>
        public static bool[] DrawCheckBoxGrid(bool[] checkedValues, GUIContent[] content, int columns, GUIStyle style, params GUILayoutOption[] options)
        {
            return DrawGenericGrid((e, i, s, o) => GUILayout.Toggle(e[i], content[i], style, options), checkedValues, content, columns, style, options);
        }

        /// <summary>
        /// Draw a grid of controls using a draw callback similar to SelectionGrid.
        /// </summary>
        /// <param name="drawCallback">Specifies a draw callback that is responsible for performing the actual drawing.</param>
        /// <param name="values">Specifies the values of the controls.</param>
        /// <param name="content">The content for each individual control.</param>
        /// <param name="columns">The number of columns in the grid.</param>
        /// <param name="style">The style to be applied to each control.</param>
        /// <param name="options">Specifies layout options to be applied to each control.</param>
        /// <returns>Returns the value for each control.</returns>
        /// <remarks><p>Controls are drawn top to bottom, left to right.</p>  </remarks>
        /// <exception cref="IndexOutOfRangeException">Can occur if the size of the array is too small.</exception>
        /// <exception cref="ArgumentNullException">If the drawCallback is null.</exception>
        public static T[] DrawGenericGrid<T>(Func<T[], int, GUIStyle, GUILayoutOption[], T> drawCallback, T[] values, GUIContent[] content, int columns, GUIStyle style, params GUILayoutOption[] options)
        {
            if (drawCallback == null)
            {
                throw new ArgumentNullException("drawCallback");
            }

            GUILayout.BeginVertical();
            var rowIndex = 0;
            var columnIndex = 0;
            var index = rowIndex * columns + columnIndex;

            GUILayout.BeginHorizontal();
            while (index < values.Length)
            {
                // draw control
                values[index] = drawCallback(values, index, style, options);

                // move to next column
                columnIndex++;

                // if passed max columns move down to next row and set to first column
                if (columnIndex > columns - 1)
                {
                    columnIndex = 0;
                    rowIndex++;

                    // remember to start a new horizontal layout
                    GUILayout.EndHorizontal();
                    GUILayout.BeginHorizontal();
                }

                // re-calculate the index
                index = rowIndex * columns + columnIndex;
            }
            GUILayout.EndHorizontal();

            GUILayout.EndVertical();
            return values;
        }
    } 

Here is a simple example of how to use the draw methods

var emptyContent = new[] { GUIContent.none, GUIContent.none, GUIContent.none, 
                            GUIContent.none, GUIContent.none, GUIContent.none, 
                            GUIContent.none, GUIContent.none, GUIContent.none };

GUILayout.BeginVertical(GUILayout.MinWidth(128));
rule.IgnoreUpper = GUILayout.Toggle(rule.IgnoreUpper, "Upper Neighbors");
rule.NeighborsUpper = ControlGrid.DrawCheckBoxGrid(rule.NeighborsUpper, emptyContent, 3, GUI.skin.button, GUILayout.MaxWidth(32), GUILayout.MaxHeight(32));
GUILayout.EndVertical();

MEFHelpers provides a helper class that provides a static method to make MEF composition easier.

    /// <summary>
    /// Provides a helper class for MEF composition.
    /// </summary>
    public sealed class MEFHelpers
    {
        /// <summary>
        /// Composes MEF parts.
        /// </summary>
        /// <param name="parts">The composable object parts.</param>
        public static void Compose(params object[] parts)
        {
            Compose(parts, new string[0]);
        }

        /// <summary>
        /// Composes MEF parts.
        /// </summary>
        /// <param name="searchFolders">Provides a series of search folders to search for *.dll files.</param>
        /// <param name="parts">The composable object parts.</param>
        public static void Compose(IEnumerable<string> searchFolders, params object[] parts)
        {
            // setup composition container
            var catalog = new AggregateCatalog();

            // check if folders were specified
            if (searchFolders != null)
            {
                // add search folders
                foreach (var folder in searchFolders.Where(System.IO.Directory.Exists))
                {
                    catalog.Catalogs.Add(new DirectoryCatalog(folder, "*.dll"));
                }
            }

            // compose and create plug ins
            var composer = new CompositionContainer(catalog);
            composer.ComposeParts(parts);
        }
    }

A usage scenario is provided below

    public class KissCSMEFComposer  
    {
        [ImportMany(typeof(IProcessor))]
        public List<Lazy<IProcessor>> StringProcessors;

        [ImportMany(typeof(ICommandRepository))]
        public List<Lazy<ICommandRepository>> CommandRepository;
    }

    var composer = new KissCSMEFComposer();
    // try to connect with MEF types
    try
    {
        MEFHelpers.Compose(this.SearchFolders, composer);
    }
    catch (Exception ex)
    {
        // ERR: handle error
    }

    // register string processors
    foreach (var processor in composer.StringProcessors)
    {
        StringProcessorRepository.Instance.Register(processor.Value);
    }

    // etc ...

The code below can be used to log performance of your code.

    using System.Collections.Generic;
    using System.Diagnostics;

    /// <summary>
    /// Provides a simple performance testing class that utilizes <see cref="Stopwatch"/>.
    /// </summary>
    /// <typeparam name="T">The type that will be used as the indexer.</typeparam>
    public class PerformanceTesting<T>
    {
        /// <summary>
        /// Provides a model that contains timer information.
        /// </summary>
        private class TimerModel
        {
            /// <summary>
            /// Used to record performance timings.
            /// </summary>
            public readonly Stopwatch Timer;

            /// <summary>
            /// Used to record how many times the <see cref="Timer"/> has been started.
            /// </summary>
            public int Count;

            /// <summary>
            /// Used to store the enabled state.
            /// </summary>
            private bool enabled;

            /// <summary>
            /// Gets or sets a value whether or not this timer if enabled.
            /// </summary>
            /// <remarks>If <see cref="Timer"/> has been started and Enabled is set to false the timer will be stopped.</remarks>
            public bool Enabled
            {
                get
                {
                    return this.enabled;
                }

                set
                {
                    this.enabled = value;

                    // be sure to stop the timer if disabled
                    if (!value && this.Timer.IsRunning)
                    {
                        this.Timer.Stop();
                    }
                }
            }

            /// <summary>
            /// Default constructor.
            /// </summary>
            public TimerModel()
            {
                this.Timer = new Stopwatch();
                this.enabled = true;
            }
        }

        /// <summary>
        /// Holds a reference to a singleton instance.
        /// </summary>
        private static PerformanceTesting<T> singleton;

        /// <summary>
        /// Used to store various timer information.
        /// </summary>
        private readonly Dictionary<T, TimerModel> timers;

        /// <summary>
        /// Default constructor.
        /// </summary>
        public PerformanceTesting()
        {
            this.timers = new Dictionary<T, TimerModel>();
        }

        /// <summary>
        /// Creates a new timer.
        /// </summary>
        /// <param name="key">The unique key for the timer.</param>
        /// <remarks>It is best to create the timer at the start of the application getting it ready for use.</remarks>
        public void Create(T key)
        {
            this.timers.Add(key, new TimerModel());
        }

        /// <summary>
        /// Creates a new timer for each key.
        /// </summary>
        /// <param name="keys">The unique keys for the timers.</param>
        /// <remarks>It is best to create the timer at the start of the application getting it ready for use.</remarks>
        public void Create(T[] keys)
        {
            foreach (var key in keys)
            {
                this.timers.Add(key, new TimerModel());
            }
        }

        /// <summary>
        /// Returns the total ticks that this timer has observed.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <returns>Returns a time value in ticks.</returns>
        public long TotalTicks(T key)
        {
            var model = this.timers[key];
            return model.Timer.ElapsedTicks;
        }

        /// <summary>
        /// Returns the total ticks that this timer has observed.
        /// </summary>
        /// <param name="keys">The keys to the timers information.</param>
        /// <returns>Returns the sum of the time values in ticks.</returns>
        public long TotalTicks(T[] keys)
        {
            long total = 0;
            foreach (var key in keys)
            {
                var model = this.timers[key];
                total += model.Timer.ElapsedTicks;
            }

            return total;
        }

        /// <summary>
        /// Gets the start count.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <returns>The number of times the timer has started.</returns>
        public int GetStartCount(T key)
        {
            var model = this.timers[key];
            return model.Count;
        }

        /// <summary>
        /// Gets the start count for specified timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <returns>The sum total of times all specified the timers have started.</returns>
        public int GetStartCount(T[] keys)
        {
            int total = 0;
            foreach (var key in keys)
            {
                var model = this.timers[key];
                total += model.Count;
            }

            return total;
        }

        /// <summary>
        /// Returns the total ticks that this timer has observed.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <returns>Returns a time value in milliseconds.</returns>
        public long TotalMilliseconds(T key)
        {
            var model = this.timers[key];
            return model.Timer.ElapsedMilliseconds;
        }

        /// <summary>
        /// Returns the total ticks that this timer has observed.
        /// </summary>
        /// <param name="keys">The keys to the timers information.</param>
        /// <returns>Returns the sum of the time values in milliseconds.</returns>
        public long TotalMilliseconds(T[] keys)
        {
            long total = 0;
            foreach (var key in keys)
            {
                var model = this.timers[key];
                total += model.Timer.ElapsedMilliseconds;
            }

            return total;
        }

        /// <summary>
        /// Calculates the average time in ticks that elapsed while this timer was recording.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <returns>Returns the average time in ticks that elapsed between each start and stop.</returns>
        public long AverageTicks(T key)
        {
            var model = this.timers[key];
            return model.Timer.ElapsedTicks / model.Count;
        }

        /// <summary>
        /// Calculates the total average time in ticks that elapsed while the specified timers were recording.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <returns>Returns the total average time in ticks that elapsed between each start and stop for all the specified timers.</returns>
        public long AverageTicks(T[] keys)
        {
            long total = 0;
            var count = 0;
            foreach (var key in keys)
            {
                var model = this.timers[key];
                total += model.Timer.ElapsedTicks;
                count += model.Count;
            }

            return total / count;
        }

        /// <summary>
        /// Calculates the average time in milliseconds that elapsed while this timer was recording.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <returns>Returns the average time in milliseconds that elapsed between each start and stop.</returns>
        public long AverageMilliseconds(T key)
        {
            var model = this.timers[key];
            if (model.Count == 0)
            {
                return 0;
            }

            return model.Timer.ElapsedMilliseconds / model.Count;
        }

        /// <summary>
        /// Calculates the total average time in milliseconds that elapsed while the specified timers were recording.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <returns>Returns the total average time in milliseconds that elapsed between each start and stop for all the specified timers.</returns>
        public long AverageMilliseconds(T[] keys)
        {
            long total = 0;
            var count = 0;
            foreach (var key in keys)
            {
                var model = this.timers[key];
                total += model.Timer.ElapsedMilliseconds;
                count += model.Count;
            }

            if (count == 0)
            {
                return 0;
            }

            return total / count;
        }

        /// <summary>
        /// Removes the specified timers.
        /// </summary>
        /// <param name="keys">The keys to the timers that will be removed.</param>
        public void Remove(T[] keys)
        {
            foreach (var key in keys)
            {
                this.timers.Remove(key);
            }
        }

        /// <summary>
        /// Removes a timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        public void Remove(T key)
        {
            this.timers.Remove(key);
        }

        /// <summary>
        /// Resets all the timers.
        /// </summary>
        public void ResetAll()
        {
            foreach (var pair in this.timers)
            {
                pair.Value.Timer.Reset();
            }
        }

        /// <summary>
        /// Resets all the timers.
        /// </summary>
        /// <param name="resetCounts">If true will set each timer start count to 0.</param>
        public void ResetAll(bool resetCounts)
        {
            foreach (var pair in this.timers)
            {
                pair.Value.Timer.Reset();
                if (resetCounts)
                {
                    pair.Value.Count = 0;
                }
            }
        }

        /// <summary>
        /// Gets an array of timer keys.
        /// </summary>
        /// <returns>Returns an array of timer keys.</returns>
        public T[] GetKeys()
        {
            var keys = new T[this.timers.Count];
            this.timers.Keys.CopyTo(keys, 0);
            return keys;
        }

        /// <summary>
        /// Sets the enabled state of the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <param name="enabled">If true the timer will be enabled. If false the timer will be stopped if it is running.</param>
        public void SetEnabled(T key, bool enabled)
        {
            var model = this.timers[key];
            model.Enabled = enabled;
        }

        /// <summary>
        /// Sets the enabled state of the specified timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <param name="enabled">If true the timers will be enabled. If false the timers will be stopped if they are running.</param>
        public void SetEnabled(T[] keys, bool enabled)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                model.Enabled = enabled;
            }
        }

        /// <summary>
        /// Gets the enabled state of the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        public bool IsEnabled(T key)
        {
            var model = this.timers[key];
            return model.Enabled;
        }

        /// <summary>
        /// Gets the enabled state of the specified timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <param name="enabled">Will contain the enabled state for each specified key.</param>
        public void IsEnabled(T[] keys, out bool[] enabled)
        {
            var enabledStates = new bool[keys.Length];
            for (int i = 0; i < keys.Length; i++)
            {
                var model = this.timers[keys[i]];
                enabledStates[i] = model.Enabled;
            }

            enabled = enabledStates;
        }

        /// <summary>
        /// Starts the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <remarks>Will not start if the enabled state is false.</remarks>
        public void Start(T key)
        {
            var model = this.timers[key];
            if (!model.Enabled)
            {
                return;
            }
            model.Count++;
            model.Timer.Start();
        }

        /// <summary>
        /// Starts the timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <remarks>Will not start if the timers enabled state is false.</remarks>
        public void Start(T[] keys)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                if (!model.Enabled)
                {
                    continue;
                }
                model.Count++;
                model.Timer.Start();
            }
        }

        /// <summary>
        /// Stops the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        public void Stop(T key)
        {
            var model = this.timers[key];
            if (!model.Enabled)
            {
                return;
            }
            model.Timer.Stop();
        }

        /// <summary>
        /// Stops the timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        public void Stop(T[] keys)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                if (!model.Enabled)
                {
                    continue;
                }
                model.Timer.Stop();
            }
        }

        /// <summary>
        /// Resets the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        public void Reset(T key)
        {
            this.Reset(key, false);
        }

        /// <summary>
        /// Resets the timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        public void Reset(T[] keys)
        {
            this.Reset(keys, false);
        }

        /// <summary>
        /// Resets the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <param name="resetCount">If true the start count for the timer will be set to 0.</param>
        public void Reset(T key, bool resetCount)
        {
            var model = this.timers[key];
            model.Timer.Reset();
            if (resetCount)
            {
                model.Count = 0;
            }
        }

        /// <summary>
        /// Resets the timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <param name="resetCounts">If true the start count for the timers will be set to 0.</param>
        public void Reset(T[] keys, bool resetCounts)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                model.Timer.Reset();
                if (resetCounts)
                {
                    model.Count = 0;
                }
            }
        }

        /// <summary>
        /// Resets the timer start count to 0.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        public void ResetCount(T key)
        {
            var model = this.timers[key];
            model.Count = 0;
        }

        /// <summary>
        /// Resets each timer start count to 0.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        public void ResetCount(T[] keys)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                model.Count = 0;
            }
        }

        /// <summary>
        /// Restarts the timer.
        /// </summary>
        /// <param name="key">The key to the timer information.</param>
        /// <param name="resetCount">If true the start count for the timer will be set to 0.</param>
        /// <remarks>The timer will be reset then started again.</remarks>
        public void Restart(T key, bool resetCount)
        {
            var model = this.timers[key];
            model.Timer.Reset();
            if (resetCount)
            {
                model.Count = 0;
            }

            this.Start(key);
        }

        /// <summary>
        /// Restarts the specified timers.
        /// </summary>
        /// <param name="keys">The keys to the timer information.</param>
        /// <param name="resetCounts">If true the start count for the timers will be set to 0.</param>
        /// <remarks>Each timer will be reset then started again.</remarks>
        public void Restart(T[] keys, bool resetCounts)
        {
            foreach (var key in keys)
            {
                var model = this.timers[key];
                model.Timer.Reset();
                if (resetCounts)
                {
                    model.Count = 0;
                }
            }

            this.Start(keys);
        }

        /// <summary>
        /// Gets a singleton instance of the <see cref="PerformanceTesting{T}"/> class.
        /// </summary>
        public static PerformanceTesting<T> Instance
        {
            get
            {
                return singleton ?? (singleton = new PerformanceTesting<T>());
            }
        }
    }

Setting up a performance counter

#if PERFORMANCE
            var perf = PerformanceTesting<string>.Instance;
            perf.Create("ScanLines");
#endif

A sample usage

#if PERFORMANCE
                var perf = PerformanceTesting<string>.Instance;
                perf.Reset("ScanLines");
                perf.Start("ScanLines");
#endif
                this.scanner.Calculate(this.points);
#if PERFORMANCE
                perf.Stop("ScanLines");
#endif

How to report the results

#if PERFORMANCE
        public static void ReportPerformanceTimes()
        {
            var perf = PerformanceTesting<string>.Instance;
            foreach (var value in perf.GetKeys())
            {
                Debug.Log(string.Format("{0} - Total: {1}ms Average: {2} Count: {3}", value, perf.TotalMilliseconds(value), perf.AverageMilliseconds(value), perf.GetStartCount(value)));
            }

            Debug.Log(string.Format("Total Performance Times - Total: {0}ms", perf.TotalMilliseconds("ScanLines")));
        }
#endif

Some .net/mono frameworks do not support the IsNullOrWhiteSpace method. The code below provides a simple replacement.

/// <summary>
/// Indicates whether a specified string is null, empty, or consists only of white-space characters.
/// </summary>
/// <param name="value">value: The string to test.</param>
/// <returns>true if the value parameter is null or System.String.Empty, or if value consists exclusively of white-space characters.</returns>
public static bool IsNullOrWhiteSpace(this string value)
{
    if (value == null)
    {
        return true;
    }

    var index = 0;
    while (index < value.Length)
    {
        if (char.IsWhiteSpace(value[index]))
        {
            index++;
        }
        else
        {
            return false;
        }
    }

    return true;
}

Some .net/mono frameworks do not support the 3 argument GetDirectories method. The code below provides a simple replacement.

/// <summary>
/// Builds an array of folders & sub folders.
/// </summary>
/// <param name="path">The path to search.</param>
/// <param name="pattern">The search string to match against the names of files in path. The parameter cannot end in two periods 
/// ("..") or contain two periods ("..") followed by System.IO.Path.DirectorySeparatorChar or System.IO.Path.AltDirectorySeparatorChar,
/// nor can it contain any of the characters in System.IO.Path.InvalidPathChars.
///</param>
/// <param name="searchOptions">One of the System.IO.SearchOption values that specifies whether the search operation should include 
/// all subdirectories or only the current directory.
///</param>
/// <returns>A String array of directories that match the search pattern.</returns>
public static string[] GetDirectories(string path, string pattern, SearchOption searchOptions)
{
    // check if searching for all directories
    if (searchOptions == SearchOption.AllDirectories)
    {
        // add start paths to list
        var list = Directory.GetDirectories(path, pattern);
        var index = 0;
        var count = list.Length;

        // process list and add folders to end of list
        while (index < count)
        {
            var directories = Directory.GetDirectories(list[index++], pattern);
            if (directories.Length > 0)
            {
                // check if we need more space to store the directories
                if (count + directories.Length > list.Length - 1)
                {
                    Array.Resize(ref list, list.Length + directories.Length + 1000);
                }

                // add directories to end of the list
                foreach (var directory in directories)
                {
                    list[count++] = directory;
                }
            }

            // trim unused index from end of the array
            if (list.Length > count)
            {
                Array.Resize(ref list, count);
            }
        }

        return list;
    }

    // just return initial list of folder with no sub folders
    return Directory.GetDirectories(path, pattern);
}

/// <summary>
/// Provides a game object that automatically self terminates.
/// </summary>
[ExecuteInEditMode]
public class SelfTerminatingObject : MonoBehaviour
{
    /// <summary>
    /// Holds a reference to a callback that will be called just before termination.
    /// </summary>
    public Action Callback;

    /// <summary>
    /// Holds the time delay in seconds before object self terminates.
    /// </summary>
    public float Delay;

    /// <summary>
    /// Holds a time value used to determine whether it's time to self terminate.
    /// </summary>
    private DateTime lastTime;

    /// <summary>
    /// Called by Unity to update the object.
    /// </summary>
    public void Update()
    {
        this.PerformCheck();
    }

    /// <summary>
    /// Called by Unity to draw the object's GUI.
    /// </summary>
    public void OnGui()
    {
        this.PerformCheck();
    }

    /// <summary>
    /// Determines whether it's time to terminate.
    /// </summary>
    private void PerformCheck()
    {
        // check if specified time span has elapsed
        if (DateTime.Now > this.lastTime + TimeSpan.FromSeconds(this.Delay))
        {
            // run callback is specified
            if (this.Callback != null)
            {
                this.Callback();
            }

            // destroy object
#if UNITY_EDITOR
        DestroyImmediate(this.gameObject, true);
#else
            Destroy(this.gameObject);
#endif
        }
    }

    /// <summary>
    /// Creates a self terminating game object.
    /// </summary>
    /// <param name="callback">The method to be called before the object terminates.</param>
    /// <returns>Returns a reference to the game object that will self terminate.</returns>
    public static GameObject CreateUpdateCallback(Action callback)
    {
        return CreateUpdateCallback(callback, 0);
    }

    /// <summary>
    /// Creates a self terminating game object.
    /// </summary>
    /// <param name="callback">The method to be called before the object terminates.</param>
    /// <param name="delay">Specifies a delay value in seconds before the object will self terminate.</param>
    /// <returns>Returns a reference to the game object that will self terminate.</returns>
    public static GameObject CreateUpdateCallback(Action callback, float delay)
    {
        var obj = new GameObject();
        var com = obj.AddComponent<SelfTerminatingObject>();
        com.lastTime = DateTime.Now;
        com.Delay = delay;
        com.Callback = callback;

        return obj;
    }
}

This code is designed to hook into unity’s EditorApplication.update delegate.

IRun.cs

namespace CBX.CoreProjectCode.Interfaces
{
    using CBX.CoreProjectCode.Models;

    /// <summary>
    /// Provides a interface for running a <see cref="CallbackModel{T}"/> type.
    /// </summary>
    public interface IRun
    {
        /// <summary>
        /// Runs the <see cref="CallbackModel{T}"/> type.
        /// </summary>
        void Run();                    
    }
}

CallbackModel.cs

namespace CBX.CoreProjectCode.Models
{
    using System;

    using CBX.CoreProjectCode.Interfaces;

    /// <summary>
    /// Provides a modal for callbacks.
    /// </summary>
    /// <typeparam name="T">The generic type used to represent the data type.</typeparam>
    public class CallbackModel<T> : IRun
    {
        /// <summary>
        /// A reference to a callback method.
        /// </summary>
        public Action<T> Callback;

        /// <summary>
        /// A reference to some data that will be passed to the callback method.
        /// </summary>
        public T Data;

        /// <summary>
        /// Implements <see cref="IRun.Run"/> to run the callback. 
        /// </summary>
        public void Run()
        {
            this.Callback(this.Data);
        }
    }
}

EditorCallbackService.cs

namespace CBX.CoreProjectCode.Services
{
    using System;
    using System.Collections.Generic;

    using CBX.CoreProjectCode.Interfaces;
    using CBX.CoreProjectCode.Models;

    /// <summary>
    /// The editor callback service.
    /// </summary>
    public class EditorCallbackService
    {
        /// <summary>
        /// Holds a singleton instance of the <see cref="EditorCallbackService"/> type.
        /// </summary>
        private static EditorCallbackService service;

        /// <summary>
        /// Holds a list of <see cref="CallbackModel{T}"/> types that implement <see cref="IRun"/>.
        /// </summary>
        private readonly Stack<IRun> callbacks;

        /// <summary>
        /// Initializes a new instance of the <see cref="EditorCallbackService"/> class.
        /// </summary>
        public EditorCallbackService()
        {
            this.callbacks = new Stack<IRun>();
        }

        /// <summary>
        /// Returns a singleton instance of the <see cref="EditorCallbackService"/> type.
        /// </summary>
        public static EditorCallbackService Instance
        {
            get
            {
                // if no service yet exists create one
                return service ?? (service = new EditorCallbackService());
            }
        }

        /// <summary>
        /// Runs any callbacks that have been registered.
        /// </summary>
        public void Run()
        {
            while (this.callbacks.Count > 0)
            {
                var cb = this.callbacks.Pop();
                cb.Run();
            }
        }

        /// <summary>
        /// Registers a <see cref="Action{T}"/> callback.
        /// </summary>
        /// <typeparam name="T">The type of data that the <see cref="callback"/> takes as a parameter.</typeparam>
        /// <param name="callback">A reference to a callback.</param>
        public void Register<T>(Action<T> callback)
        {
            this.Register(callback, default(T));
        }

        /// <summary>
        /// Registers a <see cref="Action{T}"/> callback.
        /// </summary>
        /// <typeparam name="T">
        /// The type of data that the <see cref="callback"/> takes as a parameter.
        /// </typeparam>
        /// <param name="callback">
        /// A reference to a callback.
        /// </param>
        /// <param name="data">
        /// The data that will be passed as a parameter when the <see cref="callback"/> is invoked.
        /// </param>
        public void Register<T>(Action<T> callback, T data)
        {
            if (callback == null)
            {
                throw new ArgumentNullException("callback");
            }

            var modal = new CallbackModel<T> { Callback = callback, Data = data };
            this.callbacks.Push(modal);
        }

        /// <summary>
        /// Registers a <see cref="Action"/> callback.
        /// </summary>
        /// <param name="callback">A reference to a callback.</param>
        public void Register(Action callback)
        {
            this.Register<object>(x => callback(), null);
        }
    }
}

Usage scenario …

    [InitializeOnLoad]
    public class EditorInitialization
    {
        /// <summary>
        /// Holds a value indicating whether the RunCallbacks method has been called at least once before.
        /// </summary>
        private static bool ranOnce;

        /// <summary>
        /// Initializes static members of the <see cref="EditorInitialization"/> class.
        /// </summary>
        static EditorInitialization()
        {
            EditorApplication.update += RunCallbacks;
        }

        private static void RunCallbacks()
        {
            if (!ranOnce)
            {
                // setup the settings system
                SetupSettings();

                // load localization strings
                LoadLocalizationData();

                ranOnce = true;
                return;
            }

            // invoke callbacks from editor callback service     
            EditorCallbackService.Instance.Run();
        }
    }

Source –> https://gist.github.com/chkn/4748252

using System;
using System.Linq;

public static class JSON 
{
    public static string Stringify (object obj)
    {
        string str;
        if (obj == null) return "null";
        if (obj is ValueType) return obj.ToString ().ToLowerInvariant ();
        if ((str = obj as string) != null) return System.Text.RegularExpressions.Regex.Escape (str);

        // assume it's a POCO
        return "{" + string.Join (",",
            from p in obj.GetType ().GetProperties ()
            let json = (JSONAttribute) p.GetCustomAttributes (typeof (JSONAttribute), true).FirstOrDefault ()
            where json != null
            select "\"" + (json.Key ?? p.Name) + "\":" + Stringify (p.GetValue (obj, null))
        ) + "}";
    }
}

public class JSONAttribute : Attribute
{
    public string Key { get; set; }
    public JSONAttribute () {}    
    public JSONAttribute (string key) { Key = key; }
}

        /// <summary>
        /// Determines if this rectangle intersects with rect.
        /// </summary>
        /// <param name="rect">
        /// The rectangle to test.
        /// </param>
        /// <returns>
        /// This method returns true if there is any intersection, otherwise false.
        /// </returns>
        public bool Intersects(RectangleF rect)
        {
            return !((this.X > rect.Right) || (this.Right < rect.Left) || (this.Y > rect.Bottom) || (this.Bottom < rect.Top));
        }

        /// <summary>
        /// Replaces this RectangleF with the intersection of itself and the specified RectangleF.
        /// </summary>
        /// <param name="rect">
        /// The RectangleF with which to intersect.
        /// </param>
        public void Intersect(RectangleF rect)
        {
            this.X = Math.Max(this.Left, rect.Left);
            this.Y = Math.Max(this.Top, rect.Top);
            this.Width = Math.Min(this.Right, rect.Right) - this.X;
            this.Height = Math.Min(this.Bottom, rect.Bottom) - this.Y;
        }

        /// <summary>
        /// Returns a third RectangleF structure that represents the intersection of two other RectangleF structures. 
        /// If there is no intersection, an empty RectangleF is returned.
        /// </summary>
        /// <param name="a">
        /// A rectangle to intersect.   
        /// </param>
        /// <param name="b">
        /// B rectangle to intersect.  
        /// </param>
        /// <returns>
        /// A RectangleF that represents the intersection of a and b.
        /// </returns>
        public static RectangleF Intersect(RectangleF a, RectangleF b)
        {
            float x = Math.Max((sbyte)a.X, (sbyte)b.X);
            float num2 = Math.Min(a.X + a.Width, b.X + b.Width);
            float y = Math.Max((sbyte)a.Y, (sbyte)b.Y);
            float num4 = Math.Min(a.Y + a.Height, b.Y + b.Height);
            if ((num2 >= x) && (num4 >= y))
            {
                return new RectangleF(x, y, num2 - x, num4 - y);
            }

            return Empty;
        }

/// <summary>
/// Blends two colors together.
/// </summary>
/// <param name="color">
/// The source color.
/// </param>
/// <param name="src">
/// The blend color.
/// </param>
/// <returns>
/// Returns the result as a <see cref="Color"/> type.
/// </returns>
/// <remarks>
/// From Wikipedia https://en.wikipedia.org/wiki/Alpha_compositing -> "Alpha blending" 
/// </remarks>
public static Color Blend(this Color color, Color src)
{
    float sr = src.R / 255f;
    float sg = src.G / 255f;
    float sb = src.B / 255f;
    float sa = src.A / 255f;
    float dr = color.R / 255f;
    float dg = color.G / 255f;
    float db = color.B / 255f;
    float da = color.A / 255f;

    float oa = sa + (da * (1 - sa));
    float r = ((sr * sa) + ((dr * da) * (1 - sa))) / oa;
    float g = ((sg * sa) + ((dg * da) * (1 - sa))) / oa;
    float b = ((sb * sa) + ((db * da) * (1 - sa))) / oa;
    float a = oa;

    return new Color((byte)(r * 255), (byte)(g * 255), (byte)(b * 255), (byte)(a * 255));
}