p5js/common - Paisley refactor/improve handling of point dragging
p5js/common - Paisley refactor/improve handling of point dragging

Add supoprt for knowing which point is being dragged, and simplify the propagation of mouse events to only that item, as well as enable item-specific behavior.

This allows us to only calculate the internal helper points when the position of the Paisley (bulb) is updated, and avoid that unnecessary calcuation when moving the tail.

brianhonohan/sketchbook,brianhonohan/sketchbook,brianhonohan/sketchbook