Provides a fast signal for use where two parameters are dispatched with the signal.
new ()
dispatch (object1:T1, object2:T2):Void
head:ListenerNode<TListener>
read onlynumListeners:Int
tail:ListenerNode<TListener>
add (listener:TListener):Void
addOnce (listener:TListener):Void
remove (listener:TListener):Void
removeAll ():Void