Convert more manpages to DocBook 5 XML.

Convert more manpages to DocBook 5 XML.

Remove unused nroff-generating program and update gitignore.

See:

* https://github.com/shlomif/fortune-mod/issues/41

Made use of doclifter ( http://www.catb.org/~esr/doclifter/ ),
docmake ( https://www.shlomifish.org/open-source/projects/docmake/ ),
cmake, and Perl 5. Thanks!

The current plan is to provide the resultant nroff outputs (or easily 's/.../.../'able
templates of them) inside the source tarballs to avoid a build time dependency on
DocBook XSL and docmake.