Add the man page description line as explicit markup at the top of each
Help/manual/*.rst file and scan it from conf.py to automatically
generate the man_pages Sphinx configuration value. This reduces the
number of places that need to be changed when a new manual is added.
Make the standard --help-* options available from all command-line
tools. Drop options that are no longer supported:
--copyright, --help-full, --help-html, --help-man,
--help-compatcommands, --help-custom-modules
De-duplicate Help/manual/*.1.rst help options by using an
OPTIONS_HELP.txt file included from each manual.
Add "Synopsis", "Description", and "See Also" manual page section
headers. These are typical of .1 man section pages. Also de-duplicate
the See Also section links using a separate LINKS.txt file included from
each manual.