_QLButton / Link should show some feedback while it is thinking

(Bug, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
UX
Summary: For a good example of why, check out the Period Games Rules Page. That's now broken into sections, so it displays fast, but when you click one of the headers, it pauses for a long time, with no feedback, while it thinks.
Not sure what this should think, but probably some "working" icon, preferably an animated one from Font Awesome.