feat(Library): Use NgZone for Vis-timeline

should fix #388

because vis-timeline uses setTimeout as well as setInterval Angular
ChangeDetection will be triggered regularly. This causes
performance issues. Running the timeline outside of the zone
will not trigger the ChangeDetection all the time.

Might cause some breaking changes so this needs further testing.

components/timeline/vis-timeline.service.spec.ts

@@ -3,9 +3,12 @@ import { VisTimelineService } from './vis-timeline.service';
 
 describe('VisTimelineService Tests', () => {
   let visTimelineService: VisTimelineService;
+  const ngZoneMock: any = {
+    runOutsideAngular: (fn: () => void) => fn()
+  };
 
   beforeEach(() => {
-    visTimelineService = new VisTimelineService();
+    visTimelineService = new VisTimelineService(ngZoneMock);
   });
 
   it('throws no error when the network does not exist', () => {

components/timeline/vis-timeline.service.ts

@@ -1,4 +1,4 @@
-import { EventEmitter, Injectable } from '@angular/core';
+import { EventEmitter, Injectable, NgZone } from '@angular/core';
 import {
   DataGroupCollectionType,
   DataItemCollectionType,
@@ -133,6 +133,10 @@ export class VisTimelineService {
 
   private timelines: { [id: string]: Timeline } = {};
 
+  constructor(
+    private ngZone: NgZone
+  ) { }
+
   /**
    * Creates a new timeline instance.
    *
@@ -150,7 +154,7 @@ export class VisTimelineService {
       throw new Error(this.alreadyExistsError(visTimeline));
     }
 
-    this.timelines[visTimeline] = new Timeline(container, items, options);
+    this.timelines[visTimeline] = this.ngZone.runOutsideAngular(() => new Timeline(container, items, options));
   }
 
   /**
@@ -177,7 +181,7 @@ export class VisTimelineService {
       throw new Error(this.alreadyExistsError(visTimeline));
     }
 
-    this.timelines[visTimeline] = new Timeline(container, items, groups, options);
+    this.timelines[visTimeline] = this.ngZone.runOutsideAngular(() => new Timeline(container, items, groups, options));
   }
 
   /**