Following the change which removed angle brackets from URLs, email addresses and links, some vol 15 articles (Woods and Christensen) were left with periods obviously missing in author bios (and in one textual note in Woods). Added these, after consultation with John.

This brought up the issue of how to encode them. The obvious place is the <revisionDesc> tag, but mostly these already have items noting the start of markup and pre-publication revisions. Decided to use <item> tags in <revisionDesc>, but to mark them with an n attribute, numbered sequentially, so that any <item> tags which have an n attribute should be harvested for a Corrigenda page.