More progress on shader implementation.

Changed engine OpenGL version to 4.1.

Added OpenGL program pipeline handles.

Added fragment shaders.

Some class name changes.

src/SlatedGameToolkit.Tools/Utilities/GraphicalPlayground/MainState.cs

@@ -1,5 +1,6 @@
 using System;
 using SlatedGameToolkit.Framework;
+using SlatedGameToolkit.Framework.Graphics.OpenGL.Programs;
 using SlatedGameToolkit.Framework.Graphics.Window;
 using SlatedGameToolkit.Framework.StateSystem;
 using SlatedGameToolkit.Framework.StateSystem.States;
@@ -9,6 +10,7 @@ namespace SlatedGameToolkit.Tools.Utilities.GraphicalPlayground
     public class MainState : IState
     {
         private WindowContext window;
+        private GLShaderProgram shader;
 
         public WindowContext CurrentWindow { get { return window;}}