Ungroup operation doesn't preserve node layout

[wlsnmrk]

When creating new input nodes to preserve socket defaults, the extension does its best to place them to the left of the group node. This is already somewhat unreliable, but the ungroup operation completely destroys the visual layout of the nodes. After ungrouping nodes, the extension should move other nodes in the material to preserve their relative layout to the previously-grouped nodes. This may require waiting on redraw operations to determine the actual size of the nodes, based on some quick Stack Overflow reading.