support creation of boundaries/zones from list of entries

• this makes it easier to split creation into a two-stage process as required

• extend handling for polyBoundaryMeshEntries, faBoundaryMeshEntries with more functionality. Ensure that these are never registered.

ENH: addition writeEntry methods for polyBoundaryMesh

• simplifies streaming and collating into other files

ENH: polyMesh rereading - update owner/neighbour header information

• this avoids accidentally reading the "cells" file if the mesh has been created with NO_READ and then updated

FYI @gregorweiss

applications/test/boundaryMeshEntries/Make/files

+Test-boundaryMeshEntries.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-boundaryMeshEntries