- combined most of the unweighted and weighted decomposition routines
  such that an empty weight field is treated as uniform weighting.
  This allows default parameters and cuts down on the number of
  decompose methods.

- for topology-driven decomposition, it is now possible to pass in the
  owner/neighbour connectivity as a CompactListList directly instead
  of first creating a labelListList (which was internally repacked into
  a CompactListList in many cases).
  However, multiLevelDecomp still uses unpacking (to avoid a larger
  reworking of code).

- support direct creation of some methods (eg, random, scotch etc)
  without a dictionary

- fix incorrect neighbour face weighting (fixes #3019)

ENH: relocate calcCellCells from decompositionMethod to globalMeshData

- makes it more universally available