Phased Solver

Progress with PhasedSolver.
Turns out 3x3 beginner phase 3 can still fail.

3x3 beginner should 'mostly' work now (the 'perm of the LL corners' phase can still fail - we need to define appropriate PhaseRegex here)

Seriously re-structure the architecture in preparation for different types of Phases (PhaseRegex!)

Bugfix for the PhasedSolver app.

Make the Phases more generic - now subphases can contain any subsets of the cubits involved in the whole phase.

Solving the white cross and white corners do work now.

Solving the white cross works now.

PhasedSolver app: bugfixes.

minor

Initial commit