Blender Git Commit Log

Cycles: Merge density and color volume attributes if they both requested

This way we store quite reasonable amount of memory (density is stored as RGBA
textures, which ends up in gigabytes of RAM for hires smoke sims).

It's not really pretty implementation and we'll really need to support textures
with 1 and 3 channels instead of doing such packing, but we need to be able to
render some files here.