- with alternative faceCell addressing, use the three-parameter
  version only. This avoids potential future ambiguity with the
  two-parameter version (eg, with a label type)

ENH: add faPatchField patchInternalField() for symmetry with fvPatchField

ENH: direct reference to mesh thisDb instead of inferring

ENH: pointMesh::boundaryMesh() method (eg, similar to fvMesh)