JavaScript events for custom objects.
			[link:https://github.com/mrdoob/eventdispatcher.js Eventdispatcher on GitHub]
		
// Adding events to a custom object
var Car = function () {
    this.start = function () {
        this.dispatchEvent( { type: 'start', message: 'vroom vroom!' } );
    };
};
// Mixing the EventDispatcher.prototype with the custom object prototype
Object.assign( Car.prototype, EventDispatcher.prototype );
// Using events with the custom object
var car = new Car();
car.addEventListener( 'start', function ( event ) {
    alert( event.message );
} );
car.start();
		
		Creates EventDispatcher object.
		type - The type of event to listen to.
		listener - The function that gets called when the event is fired.
		
Adds a listener to an event type.
		type - The type of event to listen to.
		listener - The function that gets called when the event is fired.
		
Checks if listener is added to an event type.
		type - The type of the listener that gets removed.
		listener - The listener function that gets removed.
		
Removes a listener from an event type.
event - The event that gets fired.
Fire an event type.
[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]