Whisker plot interupts row hover

[mccalluc]

There is a lot of behavior associated with hovering over a row, but when the cursor is over one of the whisker plots there is no row-hover behavior. Could be fixed either with an invisible rect over the whole row, or explicitly adding hover to the whisker plots as well. (I believe that z-axis in SVG is controlled by document order: There's no way to make a latter element lower.)