Add square angles action on nodes

[finetjul]

In addition to the "square corners" action, it would be great if such feature exist on single nodes.

Sometimes ways are not straight lines but not a square either (say a parking aisle case), it is a challenge to get all the angles of the way flat or square.

It would be helpful I believe to manually select a node, and square or flatten it with regard to its neighbors.
When a node has multiple neighbors (>2), then it would only flatten/square the angle formed by the 2 lastly selected nodes.