MultiplexerListener

A derived class from Listener. Since receiving an event is characterized by a unique signature of a method (for example void receives_event1(Event1*)), it is possible to simplify the definition of the pair (Event,Listener). The use of the MultiplexerListener allows this feature, by only defining Event classes, and to listen to these events in a simple way.
The Subscriber methods to connect to any type of Event take only the event type as parameter. Using this class, it is unecessary, when creating a event of a given type, to create its corresonding listener.