Snap while dragging rooms

Now, after the room is moved, it's detached from the grid and you can't merge it with any other room except the one that is appended to it.

So please make the rooms snap to grid and other rooms, thus allowing to edit a room and then e.g. snap to an existing one, or snap to grid and treat is as if it hadn't been moved.

This would allow editing parts of the plan elsewhere and dragging them to the main building. Currently this is not possible