- the default (uninitialised) value for edge connections of -1
  could be confused with a tagged finiteArea patch, which used
  (-patchid-1) encoding. This would lead to messages about erroneous
  processor-processor addressing, but is in fact an mismatched edge
  connection.

  Now tag the finiteArea patch as (-patchid-2) to avoid this ambiguity
  and correctly generate an "Undefined connection:" message instead.

  Properly flush the VTP writers before raising a FatalError
  to ensure that they are not prematurely truncated.

Open Point:

  The base problem of "Undefined connection:" is largely related to
  multiply-connected face edges (ie, from the underlying volume mesh).
  Not easily remedied in the finiteArea generation.

TUT: basic finiteArea setup on motorBike