ptscotch - compiles into ptscotchDecomp. All thirdparty decompositionMethods
now moved out of decompositionMethods so add them explicitly to link line
for programs that need them (decomposePar, snappyHexMesh etc.)

Added compressibility support to MRFZone.
Required generalisation of the oneField concept.
Also clean-up the use of one and zero for consistency.
Simple mixerVessel2D tutorial case supplied.

BUG: compilerInstall was getting overwritten in settings.{csh,sh}

non-numeric (eg, a git or cvs version).

- place the onus on the user to provide the correct ParaView_MAJOR in
  these situations.

STYLE: Drop support for cmake older than 2.6.4 (installed in 3rdParty)

Replaced with point::max wherever possible. Is VGREAT, not GREAT so be
careful with calculations.