2 small features for a better node editing

1. A way to lock the movement of the selected nodes to just a single axis, like when moving entire objects, would really be helpful.

2. A second request is to be able to select opposite nodes, and when you drag them they will get closer to each other. Imagine it as if the selections of nodes will have a center, and, like when scaling an object and pressing alt, dragging would take each node closer to the center. It should be free dragging, or locked to one or the two axis when pressing certain hotkeys.