The idea was to basically have 3 (or whatever) seperate obstacles who are
"grouped" only for selecting, moving, deleting in the editor.
E.g. when you click on one of them, all 3 obstacles become selected and the
action is applied on all of them equally.
Basically make the editor interface treat a group of obstacles as single
obstacle, but make the game treat it as 3 seperate obstacles, like this:
http://bugs.freedroid.org/b/issue368 (note: I'll have to re-do the sketches)