Distorted Android

Add testing of MeshPolygon to the MeshFile app.

Major change: separate the notion of a TwistyObject and its Node. Now,

1) the Node stays when we change objects (this makes transitions faster)
2) it's possible to just create an Object without adding it to the Screen (now app needs to explicitly create the Node and add it to its Screen itself)

Correction

By default, do use Halo Depth (this broke the halo around a solved object in distorted-cube!)

Set possibility for the Postprocessing effects to eclipse the whole object or only work at the edges.

New API: set components centers of all components all in one go.

comment.

New BORDER effect.

Comment.

Minor