Add updateWhileAnimating option

With this option, vector batches will be recreated with every frame.
For animations, this means that vector data won't be clipped to the
extent at which the animation started.

src/ol/renderer/dom/domvectorlayerrenderer.js

@@ -209,7 +209,8 @@ ol.renderer.dom.VectorLayer.prototype.prepareFrame =
       frameState.attributions, vectorSource.getAttributions());
   this.updateLogos(frameState, vectorSource);
 
-  if (!this.dirty_ && (frameState.viewHints[ol.ViewHint.ANIMATING] ||
+  if (!this.dirty_ && (!vectorLayer.getUpdateWhileAnimating() &&
+      frameState.viewHints[ol.ViewHint.ANIMATING] ||
       frameState.viewHints[ol.ViewHint.INTERACTING])) {
     return true;
   }