Event firers

The Fluid event system is operated by instances of an "event firer" which are created by a call to fluid.event.getEventFirer():

var myFirer = fluid.event.getEventFirer(unicast, preventable);

Argument	Type	Description
`unicast` (optional)	`boolean`	If `true`, this event firer is a "unicast" event firer (see Event Types).
`preventable` (optional)	`boolean`	If `true`, this event firer represents a "preventable" action (see Event Types).

Using an event firer

Once an event firer is constructed, it can be called with the following methods:

Method	Arguments	Description
`addListener`	`listener: Function`, `namespace: String` [fluid:optional]	Registers the supplied listener with this firer. The listener is a function of a particular signature which is determined between the firer and listener of an event. The namespace parameter is an optional String which defines a key representing a particular "function" of the listener. At most one listener may be registered with a firer with a particular key. This is a similar system to that operated by the JQuery namespaced events system. For an event firer which is of type `unicast`, the namespace argument will be ignored and will default to a fixed value. The use of namespaces is highly recommended.
`removeListener`	`listener: String/Function`	Supplies either the same listener object which was previously supplied to `addListener`, or else the String representing its namespace key. The designated listener will be removed from the list of registered listeners for this fierer.
`fire`	(arbitrary)	Fires an event to all the registered listeners. They will each be invoked with the exact argument list which is supplied to `fireEvent` itself. If this is a `preventable` event, `fireEvent` may return `true` indicating that a listener has requested to prevent the effect represented by this event.