Add undo selection; tweak title for Collapse All

* realized we should add a separate entry for Undo Selection since it's useful even apart from multiple selection
* another tweak to title of the Collapse All entry :) - just realized it was misleading to call it Collapse All since it actually collapses the children of a single node, not all nodes (and also re-added the "in", which I think is useful for clarity).

@JeffryBooher - is it too late to get this in for loc?