Removed OpenTK.Graphics.Glu class (reason: deprecated upstream; most functionality provided by OpenTK math; not compatible with OpenGL 3.0+.) OpenTK.Graphics.Glu can be accessed through OpenTK.Compatibility.
Added OpenGL|ES-specific ErrorHelper classes.
Moved OpenTK.Graphics.DisplayDevice and OpenTK.Graphics.DisplayResolution to the root OpenTK namespace (reason: their functionality is not specific and does not depend on OpenTK.Graphics).
Split Graphics*Exception classes into different files.
Made GraphicsErrorException public (reason: necessary for OpenTK.Compatibility).
Updated to use GraphicsFormat instead of DisplayMode.
Updated to use ColorDepth instead of ColorMode.
Improved GameWindow Exit handling, and handling of failed context creation.
Improved WinGLContext creation code, to allow for FSAA support in the future.
Fixed several shutdown bugs in WinGLContext and GraphicsContext.
Context creation no longer relies on IGLContextCreationHack.
X11GLContext is not working at the moment.