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.

Change default version to 4.1.0 (may need to revert to 4.0.1 after
further testing of 4.1.0)

The default ParaView is now 4.0.1 pending completion of testing of 4.1.0

- otherwise there is actually no means of placing a site-site
  prefs.sh in the $WM_PROJECT_SITE/ directory

- leave bashrc/cshrc and prefs.{csh,sh} in etc/ for visibility

- use standard *.sh, *.csh endings

- need to trap possibly weird input within etc/bashrc, etc/cshrc and
  can't easily redirect stderr in csh.

- avoid editing of settings.{sh,csh}

This reverts commit c5bea524.

- this change was wished by Mattijs and/or Henry

- allow command-line settings to retain the flexibility of 'foamPV'
  alias mechanism.