* froxelizer doesn't use textures anymore
All data is stored in UBOs.
Additionally, the buffer size is no longer hardcoded at compile time.
This CL cuts in half the numbers of froxels to accommodate devices
limited to 16KiB,
* Use a specialization constant to adjust the size of froxel UBO
This really only affects OpenGL in practice because metal supports 256MB
minimum and only 3% of android devices support less than 32K, which is
what we need.
edfd06eaef