Change Author extension

There are two different forms in this extension. One changes the author of a specific revision (so everything is always singular there), while the other form allows you to change the authors of each revision of a specific page (usually multiple revisions, possibly just one if the page only has one revision). That's why there are separate sets of messages, and that's why the -multi messages are pluralized. So it is actually possible to hit the -multi message in the singular case, you'd just have to find a page with a single revision in its history and go to the form to change the authors of all revisions of that page.

I hope that makes sense?