Update the docstring.

Lots of changes to get the paragraph marking to work, and not go into
an infinite recursion.

Start to rationalize markup of method signatures; not complete.

find_all_elements():  similar to getElementsByTagName(), but operates
	on the not-quite-legal fragments we deal with here.
	Simplifies several individual transforms.

fixup_sectionauthors():  Convert \sectionauthor items to <author> just
	after the <section>'s <title>.