Distorted Android

New 'glClearColor' and 'glClearDepthf' APIs in OutputSurface. This fixes the 'transparency' regressions from last commit.

Now there's a single place one can have a look at all the Meshes being rendered to a OutputSurface: OutputSurface.renderChildren().
This will need to get modified for per-object post-processing.

Minor

Speed up shaders (both compilation and execution) by explicitly enabling only the needed effects.

Fix Crawl transparency in StarWars.

Small improvements for StarWars, but the main issue - non-working transparency of the Crawl - not solved.

Fixes for z-fighting.

Make it possible to render each DistortedNode with adjustable OpeGL state (writeing to Color, Depth,Stencil buffers, DEPTH, STENCIL, BLENDING on.off, etc)

The only operation which is now enabled 'statically' in render() is blending.

1) stop culling back face
2) reset OpenGL state beore each render (and not in onCreate)
3) Improve Matrix3D so that we can test negative Scales