move transformations to Vertex Shader

[lennart]

the current fragment shader implementations for plane, circle and tri does really stupid and inefficient 2d-collision detection to rotate objects. this can be simplified by simply rotating scaling and translating the vertices in the vertex shader stage.

However, one has to take care of the following things for images:

• need to use scaled and rotated texture coordinates
• should be drawn on an infinite plane to show clamping when scaled down (e.g. see mirrored repeat to make a nice pattern, or crazy effects from clamp to edge )