Add perspective and 3d stimuli to Stage

[cafarm]

Max asked:

"Is there a way to use a different flavor of projection matrix than the orthographic projection used by Stage? ... These perspective projection matrices only really make sense for presenting different views of a rendered 3D object ... E.g. paint the texture on the inside of a cylinder and then use a perspective projection matrix."

I started a playing around with this idea:

https://github.com/Stage-VSS/stage/compare/projection

It needs to be fleshed out.