Subscribing an event

About this task
You can subscribe an event by calling BTTEventMng.prototype.addListener(eventName, fn, scope), in which fn represents the event listener and scope represents the namespace of the listener. Take the following code as an example:
var em = new BTTEventMng();
em.addEvents("event1","event2");//publish two events named “event1” and “event2”
em.addListener("event1",listener,window);
function listener(arg){
	//alert(arg);
}