reworked surfMesh and PrimitivePatchExtra
- ditched PrimitivePatchExtra in favour of a PatchTools class that is currently just a collection of static functions. They could equally well live within PrimitivePatch itself, but isolated also has its advantages. - MeshedSurface, UnsortedMeshedSurface now have 'regions' instead of 'patches' since they are more like a faceZone for meshed surfaces than patches. This might avoid confusion at a later stage.