Distorted Android

Remove the redundant DistortedNode.onPause()

Fix the fact that back-facing surfaces were invisible.

Largely fix the non-postprocessed OIT. Still, one problem remains: back-facing surfaces seem to disappear (visible in 'Cubes')

Some progress with not-postprocessed OIT.

Progress with non-postprocessed OIT.

Status: compiles, but fails to work on both Adreno and Mali. Crashes the app (Adreno) or the whole system (Mali)

Update the 'main' shaders for OIT.

In Distorted.onCreate(), catch and re-throw exceptions, so that even is some Program fails to compile, others will still compile.

Standarize GLSL version across the whole library.

Merge branch 'order-independent-transparency'

Correct a recently introduced bug.