[CDF-277] - CCC - in an area chart, a mousemove extension point with hov...

...erable and tooltip enabled throws an error

* Updating protovis, that has fixes for two additional bugs in Area's getEventHandler
* Fixed tipsy's mousemove handlers not being prepared for handling pv.Area and pv.Line's peculiarities regarding smart segmentation and real index detection. This was working on most cases cause the two just fixed bugs in protovis were masquerading the bug in tipsy...

@diogofscmariano please review.