Magic Cube

Introduce ObjectShape - a class encapsulating a shape of a Cubit.
Make the Megaminx cubit creation a bit more standard.

Minor.

COnvert the last object, the Rex cube, to the new cubit creation scheme. Provide the new Rex mesh.

New Ivy mesh.

Convert the Ivy corner cubit to the new, 'universal' cubit creation method.

This forces deep changes to 'createRoundSolid' and the underlying 'MeshPolygon' class to make them support arbitrary Polygon 'centers of face convexity'.

Reason: the faces of this cubit are concave and such default 'center of face convexity' (which by default used to be (0,0)) turned to lie outside the face - which produces strange visual artifacts.

Corrections for the Bandaged cubit creation.

Convert bandaged Cubes to the standard mesh creation code.

Move the TwistyObject.retCubePosition() to the solver.

Standarize drawing stickers of a twisty puzzle. From now on, there's no 'sticker drawing' code in the individual classes, only some constants.

Use a trick to avoid having to correct the center sticker of the Kilominx.