Waypoints are stored as absolute canvas coords, so they stayed put when a
connected node was dragged, kinking a previously clean route. A dragged
container moved its children on screen too (their stored parent-relative
position is unchanged), so their edges were missed entirely.
onNodesChange now translates the waypoints of every edge touching a moved
node by that node's delta, propagating a container's delta to all
descendants and translating once when both endpoints ride along.
ha-relevant: yes
Fixes#279
Pouzor
3cab115a80