Don't set the new lonlat if the new zoom is not valid.

This avoids unwanted panning without zooming when using the mousewheel to zoom out on a wrapDateLine map (see #109).

lib/OpenLayers/Map.js

@@ -1749,7 +1749,12 @@ OpenLayers.Map = OpenLayers.Class({
             }
         }
         if (this.baseLayer.wrapDateLine) {
+            var requestedZoom = zoom;
             zoom = this.adjustZoom(zoom);
+            if (zoom !== requestedZoom) {
+                // zoom was adjusted, so keep old lonlat to avoid panning
+                lonlat = this.getCenter();
+            }
         }
         // dragging is false by default
         var dragging = options.dragging || this.dragging;