Added a number of new widgets and utility functions for use in the
Review Board UI rewrite.
    
The main highlights include an auto-size text area, inline editor, modal
dialog box, and tooltips. There's also a utility function for
introducing a delay in an animation sequence and one for positioning an
element to the side of another element intelligently based on the sizes
of both.

I documented some of this, but I have a ways to go for that. I'll be handling
that in a separate change.

Tested with my Review Board UI rewrite. Verified that it works on Firefox 3, and I tested earlier with IE6, IE7 and Opera. There may be some regressions since then, but I'll test again before any change goes in that uses this.