Fix up AJAX watch and enable it by default.

Fix up AJAX watch and enable it by default.

* Allow it to work for nonexistent articles (pass title instead of ID)
* Use event handlers, not javascript: URLs
* Fix bug preventing akeytt from setting tooltips for a single element
* Add jsMsg() function to wikibits to allow messages to be displayed dynamically at the top of the screen (could use dismiss button?)

Some test-cases I've thrown at it worked fine (nonexistent pages, namespaced pages, pages with funny characters), but I haven't spent seven weeks in a cave meditating on what could possibly go wrong, so there may be some kind of omission somewhere.