adding dat to frame

Playground/frame.html

@@ -24,6 +24,8 @@
     <meta name="theme-color" content="#ffffff">
 
     <script src="https://code.jquery.com/pep/0.4.2/pep.min.js"></script>
+    
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.6.2/dat.gui.min.js"></script>
     <!-- Babylon.js -->
     <script src="https://preview.babylonjs.com/cannon.js"></script>
     <script src="https://preview.babylonjs.com/Oimo.js"></script>