* Use an array for keeping track of observers. This means that observers which...

 * Use an array for keeping track of observers.  This means that observers which register earlier will be notified earlier; a plugin will therefore typically be notified before its constituent parts or created objects.  This fixes #8234, because the webkit plugin needs to update its prefs before the webkit controllers do.  A priority/sorting system could be added to allow specification of the order if needed, but it isn't at this time.
 * Retain/release protection on the preferences dictionary passed to observers, as it's possible that a change in preferences could invalidate the dictionary otherwise partway through the enumeration of observers.

git-svn-id: svn://svn.adiumx.com/adium/trunk@22304 1c916fce-81e2-0310-a464-8ca513f45935