Fire node click/hover events when mouse is over/clicks a visible node label

[computermacgyver]

If a node label is visible, it would be great to capture hovers and clicks on this label and fire these as though the node the label refers to had been hovered/clicked on itself. This is a request from users of the gephi sigma exporter (oxfordinternetinstitute/gephi-plugins#15)

[jacomyal]

Since the labels are currently drawn on a canvas, detecting labels hovering would require the labels sizes to be cached and indexed in the quadtree, which is expensive.

My best idea for this issue is, as for the edges hovering issue to wait for the SVG renderer to be implemented, or to implement a new labels renderer based on DOM.