=== 0.0.5 2012-11-08 * add github page link === 0.0.4 2012-11-08 * instance-specific method with EventEmitter.apply(instance) === 0.0.3 2012-11-08 * call listener with Object#instance_exec === 0.0.2 2012-11-07 * EventEmitter#once : call listener only first time * EventEmitter#add_listener, remove_listener === 0.0.1 2012-11-07 * implement "on" and "emit"