Fix autoscale of timeline axis.

lib/timeline/Timeline.js

@@ -218,6 +218,8 @@ Timeline.prototype.setItems = function(items) {
   this.itemsData = newDataSet;
   this.itemSet && this.itemSet.setItems(newDataSet);
 
+  this.body.emitter.emit("_change");
+
   if (initialLoad) {
     if (this.options.start != undefined || this.options.end != undefined) {
       if (this.options.start == undefined || this.options.end == undefined) {