- operator+=  : add in the listed keys
 - operator-=  : remove the listed keys
 - operator&=  : intersection of keys
 - added xfer constructor (just in case)
 - moved labelHashSet typedef to HashSet.H, for consistency with the
   wordHashSet typedef being there and since it is used so often

 - added protected storedPoints(), storedFaces() functions for non-const
   access to the data. Mixing protected non-const versions and public const
   versions of the same method does not agree with the compiler
 - better handling of triFace/face distinction

through the field algebra.

Conflicts:

    src/OpenFOAM/db/runTimeSelection/runTimeSelectionTables.H

 - now there are only 2 places to adjust the typedefs when we decide on
   better names:
     MeshedSurfacesFwd.H, UnsortedMeshedSurfacesFwd.H

     - also allow table definition to have a
     - added some comments/whitespace to make the files easier to read

 - also allow table definition to have a templated baseType
 - added some comments/whitespace to make the files easier to read

  - neither class names, nor the typedefs for the <face> and <triFace>
    instances are really decided

 - useful when the baseType isn't a typedef and thus requires the same
   template argument as the derived class

 - useful when the baseType isn't a typedef and thus requires the same
   template argument as the derived class

 - useful for avoiding links on older versions, or for 'hiding' contents

  - add static/protected member function subsections
  - static members up front, constructors/destructors next
    private/protected/public members next