NxNxN: clean up pair_edge_orbit_via_555() for Even cubes
NxNxN: clean up pair_edge_orbit_via_555() for Even cubes

dwalton76/rubiks-cube-NxNxN-solver,dwalton76/rubiks-cube-NxNxN-solver,dwalton76/rubiks-cube-NxNxN-solver