Changes for request #1243027, "Impove handling of AUTHOR section."

Changes for request #1243027, "Impove handling of AUTHOR section."
This adds support for Collab, Corpauthor, Corpcredt, Orgname,
Publishername, and Publisher. Also adds support for output of
Affiliation and its children, and support for using gentext
strings for auto-attributing roles (Author, Editor, Publisher,
Translator, etc.). Also did a lot of code cleanup and
modularization of all the AUTHOR handling code. And fixed a bug
that was causing Author info to not be picked up correctly for
metainfo comment we embed in man-page source.