Distorted Android

Improvements for texturing MeshCubes objects in two apps (in light of the recent change in default texture mapping)

1) new 'Rubik' app (skeleton)
2) MeshCubes: add support for custom texture mappings on each side (Rubik needs that!)

Some improvements to the Wind app - still does not look very realistic though :(

Correct Distort.

Fixes for some stuff discovered while making the Distort effect fully 3D:

- make MeshSphere's normal lengths be 1 (used to be 0.5)
- make the Effect3D app display precise values of the Center and Region vars.

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).

Make the Sink effect fully 3D.

Correct the z-axis of the center of fragment effects (it was inverted)

Progress with the Earth app.