Resolves request http://bugs.openfoam.org/view.php?id=2367

Patch contributed by Bruno Santos
Resolves bug-report http://bugs.openfoam.org/view.php?id=2312

Patch contributed by Bruno Santos
Resolves patch request http://bugs.openfoam.org/view.php?id=2112

FOAM_INST_DIR is the location of the OpenFOAM installation which defaults to
the directory containing the etc/bashrc,cshrc file.  If this default is
not appropriate FOAM_INST_DIR can be set explicitly.

Additionally filter $ParaView_DIR from paths in config.sh/paraview and config.csh/paraview

Resolves bug-report http://bugs.openfoam.org/view.php?id=2031

Set the environment variable "FOAMY_HEX_MESH" to build foamyHexMesh,
e.g. in ~/.OpenFOAM/dev/prefs.sh

FOAMY_HEX_MESH=yes

for consistency with etc/bashrc and etc/config.sh

See commit 711ec0e3

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

Provided by Bruno Santos
Also some general cleaning and update of comment.
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1167

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.