[CDF-315] - CCC - Tipsy tooltip - should use a single instance per chart to avoid frequent showing/hiding

* A single tooltip instance is used per chart.
* Tooltip options are stored in each mark and read by tipsy, overriding construction options.
* New tooltip.animate option, for move animation, added to jquery.tipsy.
* Tooltip markup adds a tag for the visual role icon, to avoid the need for content replacement in CSS.
* Fixed tooltip percentage text breaking into a new line.
* Fixed protovis bug in detecting if a wedge contains a point.
* Fixed tooltip CSS line height problems.
* JsDocs

@pamval please review.