Some csh versions/forks seem to have problems with line breaks inside inline subshells - #2309@OpenFOAM-Foundation

Quoting myself from http://bugs.openfoam.org/view.php?id=2309

The issue I've stumbled upon with the "csh" package "20110502-2.1ubuntu1" in Ubuntu 16.04 (dpkg -l csh) is that a single backslash within the sub-shells using `` require double backslash and not a single backslash.

The problem is that I have not seen any similar report by anyone else, including on the OpenFOAM-plus issue tracker, and since Henry must have tested the script with success with a particular version or two, I'm really intrigued as to which csh versions/forks the current implementation in OpenFOAM 4.0 and newer works on.

Anyway, attached are two possible patches for extending compatibility, for easier inspection, on possible solutions:

patch.v1 - uses double backslash inside `` sub-shells
patch.v2 - uses removes backslash from inside `` sub-shells and makes the command a single line

The affected files are only these two:

etc/config.csh/paraview
etc/cshrc

Steps to reproduce:

# While on bash:
$ cd ~/OpenFOAM/OpenFOAM-dev
$ csh
% source etc/cshrc
Invalid null command.
/OpenFOAM-dev/bin/foamEtcFile: Command not found.
/OpenFOAM-dev/bin/foamCleanPath: Command not found.
/OpenFOAM-dev/bin/foamCleanPath: Command not found.
/OpenFOAM-dev/bin/foamCleanPath: Command not found.
/OpenFOAM-dev/etc/config.csh/settings: No such file or directory.

Already tagged @Mattijs on that report. I don't know if anyone else here at OpenCFD uses csh.