Working on GLES 2

Putting in the infrastructure for GLES 2 and shaders.

This leaves an unfortunate, hopefully temporary, issue: there are separate call-chains for GLES 1 and GLES 2 rendering, starting at the GLSurfaceView. The view you choose in your layout determines the rest of the rendering "stack".

The RenderService for GLES 2 calls a different method on RequireRender, which DrawableGameObject in turn delegates to its model, which in turn uses the actual GLES 2 rendering code.

So for now, all Geometry subclasses need two versions of rendering code, for GLES 1 and GLES 2 styles.