New TileManager

This removes all tile queueing/loading specific code from Layer.Grid
and creates a new class that manages tile loading and caching.

lib/OpenLayers/Layer/Bing.js

@@ -197,20 +197,12 @@ OpenLayers.Layer.Bing = OpenLayers.Class(OpenLayers.Layer.XYZ, {
                 res.zoomMax + 1 - res.zoomMin, this.numZoomLevels
             )
         }, true);
+        if (!this.isBaseLayer) {
+            this.redraw();
+        }
         this.updateAttribution();
     },
-
-    /**
-     * Method: drawTilesFromQueue
-     * Draws tiles from the tileQueue, and unqueues the tiles
-     */
-    drawTilesFromQueue: function() {
-        // don't start working on the queue before we have a url from initLayer
-        if (this.url) {
-            OpenLayers.Layer.XYZ.prototype.drawTilesFromQueue.apply(this, arguments);
-        }
-    },
-
+    
     /**
      * Method: getURL
      *
@@ -218,6 +210,9 @@ OpenLayers.Layer.Bing = OpenLayers.Class(OpenLayers.Layer.XYZ, {
      * bounds - {<OpenLayers.Bounds>}
      */
     getURL: function(bounds) {
+        if (!this.url) {
+            return;
+        }
         var xyz = this.getXYZ(bounds), x = xyz.x, y = xyz.y, z = xyz.z;
         var quadDigits = [];
         for (var i = z; i > 0; --i) {