latex write docinfo

In the latex writer, in
	LaTeXTranslator.depart_document
might it be considered to move the docinfo section
to a separate method? Say `depart_document_docinfo`
or something like that?

Motivation: it is the only part of the method that
rst2beamer changes, but there has been churn in
the other parts of `depart_document`. (So there
was really no need for the rst2beamer method to
get out of sync as it has.)

Thanks for considering,
Alan Isaac