[uxumjyov] Programmable Rubik's subgroups

Create a Rubik's cube which can be programmed only to permit arbitrary subsets of moves, for investigations into subgroups.  Easiest would be a virtual implementation.

Also wanting only to permit certain compound moves, like ABA^-1.

Inspired by Oskar Van Deventer's Half Turn Tetra, a tremendous amount of design effort merely to do one subset (no quarter turns).