code: function() {
  		var dates = [];
  		for (var i = 0; i < this.events.length; i++) {
  			if (this.events[i].end_date) {
  				dates.push({ date: this.events[i].end_date });
  			} else {
  				dates.push({ date: this.events[i].start_date });
  			}
  		}
  		for (var i = 0; i < this.eras.length; i++) {
  			if (this.eras[i].end_date) {
  				dates.push({ date: this.eras[i].end_date });
  			} else {
  				dates.push({ date: this.eras[i].start_date });
  			}
  		}
  		TL.DateUtil.sortByDate(dates, 'date');
  		return dates.slice(-1)[0].date;
  	}
docs: Return the latest date that this config knows about, whether it's a slide or an era, taking end_dates into account.