Distorted Android

Improve the 'PostprocessTree' app. Shows bugs in postprocessing.

Simplify postprocessing buffers.

Make the postprocessing buffers static.

A little progress making the postprocessing buffers static.

Introduce possibility that an OutputSurface is backed up by a larger texture than necessary and the 'cloneSize()' method.

Improve Blur (boundaries should be more white than black)

New 'Triblur' testapp.

Shows that the Blur effect doesn't fully work (probably it is the 'blitWithDepth' function which needs to be corrected)

SSBO: now we have a more-or-less correct running average of the count of transparent fragments over the last few frames.

SSBO: correct various things.

SSBO: zero out the per-surface transparent fragment counter only when setting the surface as output for the first time in the frame.