function addListener(type, listener) {
    var me = this,
        events = me.events || (me.events = {});

    forEach(type.split(' '), function(type) {
      (events[type] || (events[type] = [])).push(listener);
    });
    return me;
  }
Registers a single listener for the specified event type(s).
@memberOf Benchmark, Benchmark.Suite
@param {String} type The event type.
@param {Function} listener The function called when the event occurs.
@returns {Object} The benchmark instance.
@example

// register a listener for an event type
bench.addListener('cycle', listener);

// register a listener for multiple event types
bench.addListener('start cycle', listener);