gl/texture: Use different parameters for cubemaps
gl/texture: Use different parameters for cubemaps

The whole system needs to be a little more configurable in general, but this
will do for the moment.

RedCraneStudio/redcrane-engine,RedCraneStudio/redcrane-engine,RedCraneStudio/redcrane-engine,RedCraneStudio/redcrane-engine