feat(EmbeddedViewer): add the loader as class property (#327)

Co-authored-by: Younes Guarssifi <younes.guarssifi@sms-group.com>

source/engine/viewer/embeddedviewer.js

@@ -84,6 +84,7 @@ export class EmbeddedViewer
         this.model = null;
         let progressDiv = null;
         let loader = new ThreeModelLoader ();
+        this.loader = loader;
         loader.LoadModel (inputFiles, settings, {
             onLoadStart : () => {
                 this.canvas.style.display = 'none';