Slight UI overhaul

Before I do the 1.0 release, I plan to add the ability to tag rules. However this adds another form element to the "rule settings" screen and lets move the "rule elements" down - which is bad as they are the more important part. So to increase the usability I think it's best to make the "rule settings" fieldgroup collapsed by default - except when the rule is created.

I've just done so, so you can check it out using the dev snapshot. Feedback welcome!

One possible issue I see with that is that the used event isn't so visible any more. What's completely missing from the UI is a list of available variables or something like that, do you think we should add it somewhere? Suggestions welcome!

Anyway, I don't plan to put much effort in the UI overhaul now, maybe later on (post 1.0) though.