Adding ZoomBox and OSM fallback layer

Using the new defaults, we don't need to pass options to the Navigation
control anymore. As a side effect, we get ZoomBox, but need to add css for
it to work properly. For users outside Vienna, an OSM fallback layer was
added which gets activated when the viewport does not intersect Vienna.

examples/mobile-wmts-vienna.css

@@ -30,12 +30,27 @@ html, body, #map {
     perspective: 1000;
 }
 
+/* Tile fade animation */
 .olLayerGrid .olTileImage {
     -webkit-transition: opacity 0.2s linear;
     -moz-transition: opacity 0.2s linear;
     -o-transition: opacity 0.2s linear;
     transition: opacity 0.2s linear;
 }
+
+/* Zoom Box */
+.olHandlerBoxZoomBox {
+    border: 2px solid red;
+    position: absolute;
+    background-color: white;
+    opacity: 0.50;
+    font-size: 1px;
+    filter: alpha(opacity=50);
+}
+.olDrawBox {
+    cursor: crosshair;
+}
+
 div.olControlAttribution {
     position: absolute;
     font-size: 10px;