Added RenderableObject.Render() in preperation for refactor.
Renamed RenderableObject to IRenderable.
IRenderable objects are now in charge of their rendering.
IRenderer is in charge of IRenderables.
Cube now generates index and vertex buffers.
Removed transform caching in Cube.
Everything is moved into IRenderable/Cube.
Added GL.Viewport call to RenderFrame().
Removed GL.Viewport call in OnResize event.
Cube now is a unit triangle.
Removed per-vertex colors.
Transforms work.
Merge pull request #1 from mtwilliams/master

Refactor rendering into IRenderer and IRenderable.Render.