Distorted Android

Relax requirements on when we can call DistortedEffects.setMax().

Before this change one had to call it before creation of shaders and before any of the DistortedEffects classes got created.
This commit removes the second requirement so now with setMax it's just like with enabling effects: it's best done in onSurfaceCreated.

Massive: make the coordinate system agree with that of OpenGL (i.e. invert the Y axis).

Redefine the Vertex Region from (x,y,r,unused) to (x,y,z,r). This takes into account the 'Z', which makes it possible to warp only one side of a 3D Mesh like Sphere.

Also corresponding changes in applications.

Fully move the Meshes to their own package.

Convert everythig to GLES31 (there were some GLES30 remnants)

I am pretty sure this time the flashing issues on Mali T880 r12 driver are finally fixed.

The fix: a queue of FBOs render to, just like before, but this time in DistortedScreen we blit not the current FBO, but the one computed several frames ago.

This of course introduces a delay and uses more memory, but it appears to work and does not seem to have any effects on speed.

Move all the knowledge about Vertex and Fragment effects to their respective classes.

Change of API: move setting the EGL context back to the APP.

Small API simplification.

Bugfixes for the recent 'Effect classes' API change.