ENH: simple detection for collapsed block descriptions

- switch from default topology merge to point merge if degenerate
  blocks are detected. This should alleviate the problems noted in
  #1862.

  NB: this detection only works for blocks with duplicate vertex
      indices, not ones with geometrically duplicate points.

ENH: add patch block/face summary in blockMesh generation

- add blockMesh -verbose option to override the static or dictionary
  settings.  The -verbose option can be used multiple times to increase
  the verbosity.

ENH: extend hexCell handling with more cellShape-type methods

- allows better reuse in blockMesh.
  Remove blockMesh-local hex edge definitions that shadowed the
  hexCell values.

ENH: simplify some of the block-edge internals