Core profile compatible basic scene rendering.

Adds a shader to render an untransformed scene. renderGLGeometry is not used any more and replaced by generated triangles stored in a GLVertexBuffer.

The GLVertexBuffer has a new attribute to decide whether a core profile compatible rendering has to be performed.

Currently windows and EffectFrames can make use of the new shader.
The shader contains a debug mode which colours all rendered fragments in green. It is currently enabled in scene_opengl.
Rendering transformed geometries (without shader) is currently broken.