Upgrade jQuery and replace jQuery extensions

Use of jQuery extensions was predicated on the assumption that we could
effectively isolate our modifications of jQuery from other users on the page.
This required use of `jQuery.sub()`, which has been deprecated since jQuery 1.7
and has finally been removed in 1.9.

This PR removes Annotator's use of `jQuery.sub()`. I haven't yet had a chance to
properly user test these changes, but tests pass. Please do check out the code
and make sure it's at least sane before merging!