Cleaned up forums.js. As discussed in e-mail, changed generic function names such as "toggle()" to "forums_toggle()" to reduce the odds of future name clashes causing as much confusion and embarrassment as the recent ones in zen and forums did. Made formatting consistent. Got rid of template::head calls to load unused javascript which just made the code more confusing.
Behavior matches .LRN 2.2 behavior, the arrow on a message collapses or expands that message only, not its subtree. Subtree would probably be better (and I swear it did, once upon a time) but that will have to wait for the future if people want it.
Got rid of Victor's terribly broken button stuff, and got simple open/close message to work. However it only affects the one message, I thought it's supposed to open/close subtrees ...