added function to remove listener from listeners in EventEmitter and updated it to use Listener class.
adding a listener now returns the ID of the listener which is used to remove it.
other:
ListenerCount() returns the number of listeners
made listeners public
added function to remove listener from listeners in EventEmitter and updated it to use Listener class. adding a listener now returns the ID of the listener which is used to remove it. other: ListenerCount() returns the number of listeners made listeners public