fix for #795 - all layers now have a redraw() method that simply redraws them no matter whether the extent or parameters or zoom has changed. Big big thanks to tim schaub for not only taking the time to listen to my relentless (and often cracked) brainstorming about this ticket and for taking the time out to review the final patch.... but above and beyond the call of duty, adding *tests* for this patch. real ace. top knotch.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@3582 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -518,9 +518,7 @@ OpenLayers.Map.prototype = {
                 layer.setVisibility(false);
             }
         } else {
-            if (this.getCenter() != null) {
-                layer.moveTo(this.getExtent(), true);   
-            }
+            layer.redraw();
         }
 
         this.events.triggerEvent("addlayer");