Ported the code for the new XML output formats to the live site; in the process, I noticed more contexts in which it should not appear (mdt list pages, for instance), so added a trap that only shows it if there is a real XML source document; and I added a page documenting the formats, and linked that from the bottom of the menu. I think this is finished now.

Note to self: the CSS and JS that handles those three buttons (Page Contents, Credits and See XML) is pointlessly repetitive and could be streamlined easily.