Distorted Android

First attempt at the MeshBase.apply(VertexEffect) API.

Remove the MeshBase.{set/get}Stretch API altogether.

Change the Postprocessing effects: separate the radius and the halo.
Reason: we needed a way to specify the size of the halo around a postprocessed object; before it was automatically (and not very correctly) computed from the radius - before we knew the size of the object's bounding box, so this automatic computation was possible. Now we're removing the MashBase.getBounding(0 API, so the size of the halo has to be explicitly given by the user. This way is more correct anyway and gives the user more control (as the Multiblur app proves!)...

A lot of changes.

1) main vertex shader: remove support for degree_object. This functionality will hopefully come back when we introduce other than circular regions.
2) MeshBase: remove the need to set a Bounding box (this is the point of the whole thing - we wanted to get rid of this so that the advances in MeshJoined will be easier)...

Lower requirements - now only OpenGL ES 3.0 is required; if running on such platform, OIT part of the API ( which is the only one which actually requires 3.1) is switched off.

Fixes for the Projection matrix, FOV.

There was a confusion between the Projection of the Node onto the Screen, and the Projection of the Cubits on the Node.

Further corrections.

Correct the Rubik app for the recent changes to the library's Node.

Hide the InternalSurface class inside its package.

Convert RubikCube to the new V&F center schema!