hexRef4.C reflecting both legs of split

In test cases sent to me, it seems some meshes require that in cases of the switch at line 1185 '+1',' -2' need a reversed face, and on other meshes, it is the opposite, with '-1','+2' requiring the switch. To facilitate the easy changing, a bool has been set, with each of the 4 switch cases now checking the bool and setting the face to it's reverse, or leaving it, as appropriate.

When I understand what makes meshes require one setting or the other, I anticipate this could be tested for, and set automatically (or preferably, optimised out). Until that point, the bool allows easy changing from one setup to the other.

The readme will be updated to reflect this change.