…BITSPub#381)

Hopefully the structure of the new setup should be obvious but I will explain
some changes here:

* Renamed base dir from 'developers_guide/' to 'guides/'.  The two new
  documents are guides/users_guide/TribitsUsersGuide.rst and
  guides/maintainers_guide/TribitsMaintainersGuide.rst.  (The latter has file
  names and line numbers for all documented macros and functions and the former
  does not.  See updated abstract and Introduction sections in both documents
  for more details.)

* Split up TribitsDevelopersGuide.rst into:
   - TribitsCoreDetailedReference.rst
   - TribitsDesignConsiderations.rst
   - TribitsDevelopersGuide.rst
   - TribitsFAQ.rst
   - TribitsGuidesBody.rst
   - TribitsGuidesReferences.rst
   - TribitsHistory.rst
   - TribitsMacroFunctionDocTemplate.rst
   - TribitsPackageNotCMakePackage.rst
   - TribitsToolsDocumentation.rst

* Fixed up the shared text to work for both documents.

* Renamed driver generate-dev-guide.sh to generate-guides.sh and take
  arguments 'all' or 'md' or 'ug'.

pdflatex hangs currently.

…#381)

These are not needed anymore.  All of this has been transitioned to other
files in the new documents.

No sense leaving these in visible text at this point.

…SPub#381)