Add new Javascript observer

Output render progress onto the rendered map using Javascript
A minimum period between updates can be specified

overviewer_core/data/js_src/views.js

@@ -108,7 +108,26 @@ overviewer.views.CoordboxView = Backbone.View.extend({
     }
 });
 
-
+overviewer.views.ProgressView = Backbone.View.extend({	
+    initialize: function() {
+        this.el.id = 'progressDiv';
+        this.el.innerHTML = 'Current Render Progress';
+        overviewer.map.controls[google.maps.ControlPosition.BOTTOM_RIGHT].push(this.el);
+        this.hidden = true;
+    },
+    updateProgress: function() {
+        e = this;
+        $.getJSON('progress.js', null, function(d){
+            e.el.hidden = false;
+            e.el.innerHTML = d['message'];
+            if (d.update > 0) {
+                setTimeout("e.updateProgress()", d.update);
+            } else {
+                e.el.hidden = true;
+            }
+        });
+    }
+});
 
 /* GoogleMapView is responsible for dealing with the GoogleMaps API to create the 
  */