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.
