- Follow similar pattern as per boost/CGAL with the '*-none' to disable,
  and '*-system' for system installations.

  Also support central non-ThirdParty installations by specifying the
  version as "*-system", but also providing the fully qualified
  *_ARCH_PATH too.

--
ENH: Verify label and scalar sizes used in the metis header.

- ensure they match with expected values, which can be obtained via
  the OpenFOAM definitions for WM_LABEL_SIZE and WM_PRECISION_OPTION

Patch contributed by Bruno Santos
Resolves text report http://bugs.openfoam.org/view.php?id=2089

etc/config.sh/scotch: Added $WM_PRECISION_OPTION for consistency

etc/config.sh and etc/config.csh

This structure is more convenient to add support for other shells, e.g. zsh, fish etc.

Resolves feature request to simplify support for other shells in
http://www.openfoam.org/mantisbt/view.php?id=1232

To compile with 64bit labels set

WM_LABEL_SIZE=64

in ~/OpenFOAM/dev/prefs.sh

source ~/.bashrc

then Allwmake in OpenFOAM-dev.

This will build into for example OpenFOAM-dev/platforms/linux64ClangDPInt64Opt

If WM_LABEL_SIZE is unset or set to 32:

WM_LABEL_SIZE=32

the build would be placed into OpenFOAM-dev/platforms/linux64ClangDPInt32Opt

Thus both 32bit and 64bit label builds can coexist without problem.

- use standard *.sh, *.csh endings

- drop FOAM_MPI_LIBBIN variable in favour of FOAM_MPI from which
  two different locations can be determined.

  Previously there was something like this:

      FOAM_MPI_LIBBIN = $FOAM_LIBBIN/openmpi-1.5.1

  We now instead determine the locations from the FOAM_MPI directly:

      FOAM_MPI=openmpi-1.5.1

          $FOAM_LIBBIN/$FOAM_MPI     -> OpenFOAM  mpi-related
          $FOAM_EXT_LIBBIN/$FOAM_MPI -> ThirdPary mpi-related

ENH: relocate ParaView libraries and plugins back under FOAM_LIBBIN

- as discussed with Mattijs

- NB: A csh version is not needed, since the values here are only
      sourced during the wmake process

- Also adjusted formatting of usage to match what argList generates

- simplified the logic
- provide direct link to the respective scripts
- provide help from the respective scripts