CONFIG: inline _foamEval within <etc/config.sh/setup>

- previously a function (unlike the csh version) but since bashrc and
  setup have been split -> replace with inline definition

STYLE: formatting/wording for openfoam starters

TUT: simplify controlDict modification, add default substitution

ENH: accept '/' for end-of-options terminator (etc/openfoam)

- makes the application or service more apparent.
  * eg.  /usr/bin/openfoam / blockMesh
  * vs.  /usr/bin/openfoam -- blockMesh

  Accept lone '-' as the end-of-options terminator, as per bash

- Adjust handling of openfoam '-c' option to flag that a command-string
  will appear, but continue with option parsing.
  Consistent with bash definition.