Port all the 'non-controversial' changes from order-independent-transparency branch.
Postprocessing buffers mBuffer[] are now shared among all postprocessing operations. This saves a lot of memory, but also means that when doing each particular postprocessing, the textures backing up the mBuffer might be too large. We need to fix two things here: when outputting to those too large textures, we need to adjust the Viewport, and when binding those too large textures as input - we need to adjust the TexCoords to compensate....
Move on to Stencil on both stages of the BLUR + separate 'blit with depth'.
This works wonders on Nexus 5X ( r=50 quality=HIGHIEST 1,4,8 cubes: 59.3,43.6,41.0 FPS! ) but it somehow fails to clear the DEPTH and STENCIL buffers on Nexus 4....