Add support for animated panning, with most of the work done by Pierre, thx pierre! panTo method now animates when moving. (Closes #110)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@6111 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

tests/Layer/test_Grid.html

@@ -542,7 +542,7 @@
         map.zoomIn();
         var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
         t.eq(bounds.toBBOX(), "-180,-90,0,90", "get tile bounds returns correct bounds"); 
-        map.pan(200,0);
+        map.pan(200,0, {animate:false});
         var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
         t.eq(bounds.toBBOX(), "0,-90,180,90", "get tile bounds returns correct bounds after pan"); 
     }