TODO:
- maybe image array loader should go into TextureCube.js so that people could just reuse the code
- it may be worth to be able to specify different combination of environment map and underlying material (in single render pass),
currently color/color map/environment map are multiplied, though addition also produces very interesting looking materials
Almost done porting CanvasRenderer to the new material system (plus some performance gains on the way :D)
`Color` now handles hex with no alpha byte (probably there is a nicer way of doing it...)