Use void.class to determine how the event handler type is defined

The dummy class USE_PARAMETER was necessary when the IEvent interface
still existed, as void.class could not be used as a Class<? extends
IEvent>. As no explicit reference to USE_PARAMETER should be present
anywhere, a proper deprecation would've made little sense.

 		this.listener	= listener;
 		this.method		= method;
-		useParameter	= annotation.value() == USE_PARAMETER.class;
+		useParameter	= annotation.value() == void.class;