'=prime=counter clockwise
This is a brute force "meet in the middle" solver, working from both the unsolved-cube-state and the solved-cube-state, but with steps. centers are fixed. BETA
Any Cube can theoretically be solved in 20 moves. 90% can be solved in 18 moves, but this would take a lot of time and memory.
This is an experiment to break this up in steps to get a shortish solution, a "progress" based solver, working from layer to layer.