Distorted Android

Correct a bug where postprocessed objects would not re-appear after the app went briefly to the background.

Switch on Stencil in Postprocessing.

This is a clear win on Nexus 5X; on Nexus 4 it is debatable - faster on loads where area to be postprocessed is not much (~20% ?) of the screen; slower otherwise.

Move to a new way to detecting depth of postprocessing halos.
This switches off stenciling (hopefully temporarily!)

10% speedup with postprocessing.

Beginnings of support for multi-COLOR attachment Framebuffers.
This will be used in OutputSurface's Postprocessing Buffer.

Some improvements to DistortedRenderState.

minor

Fix Stencil in Postprocessing with lower than HIGHEST quality: now any quality works.

Progress with Stencil in Postprocessing: stencil during the 1st stage postprocess (buffer1->buffer2) works now, provided quality is HIGHEST.
(lower quality --> render errors, looks like Stencil is not set up correctly then)

Progress with Stencil in Postprocessing (doesn't work still)