Add Clipplanes to Camera

[klepto2]

As the title said. In the header source, there is already a outcommented 

void SetClipPlane(const int index, const Plane& p);

function. 

While this might not be needed for many people, it is a nice and simple feature. I would need it for a deifferent approach for the water renderer to support realtime reflections without ssr (while ssr is nice, it has some downsides and needs a lot of tweking to look right in larger environments.) and proper refraction without the need to modify the integrated refraction shader.

[Josh]

See Camera::SetClipPlane and CameraClipPlane0 in CameraInfo.glsl.