Fix #152: pointerleave/click not consistently triggering

[mcraeynest]

This resolves two issues: (#152 / #36)

• After hovering over a block, the block never shrinks back to its original size
• For the click to trigger, you had to click twice on an element

It looks like re-inserting the element in the DOM breaks mouse interactions.

Compare here with the original MoveToFront implementation:
https://wbkd.github.io/d3-extended/moveToFront.js.html

I tested the demo page with 20.000 segments on a single line, and did notice any significant difference in performance.