Updates meshing function for the full annulus
- Fixes a problem with the flagging of tangential edges where the
annulus is "glued" together; re-inserted edges were all markes as inner.
- Removes old version of MeshAnnulus() that had CRISSCROSS hardcoded.
- Updates MeshGenTest to test all four meshing flavours.
- Introduces hollowFlag enum in MeshInfo class for setting in a mesh generator
flagInnerBoundary, flagInterior, flagOuterBoundary for closed and hollow
domains such as the full annulus and the thick spherical shell. MeshAnnulus()
now used these.
- Extends documentation.
- Also fixes clipping of CRISSCROSS and CROSS picture for MeshRectangle()