ENH: upgrade to env. variable to ensight9 (current version)

This appears to be a long-standing bug!?, since it was also in the
paraview-2 reader.

- avoids a full rebuild for simple documentation changes

- foamApps  == app
- foamSol   == sol
- foamTuts  == tut
- foamUtils == util

- having all utilities available ASAP is more important than having
  all solvers immediately

Useful for in parallel if it cannot find processor*/constant/polyMesh/points
and decides to read undecomposed constant/polyMesh/points...

- removed globalPointPatch*
- removed pointPatchInterpolate*
since all is now inside volPointInterpolation.

- use .obj files for debugging purposes instead.

- operator[] with label -> get args at index
- operator[] with word  -> get named option

- also update links from opencfd.co.uk -> openfoam.com

- deprecate argList::additionalArgs() method and remove uses of it

- also provide size() method, which returns the number of arguments

- make centrally available via #include "addOverwriteOption.H"