Merge pull request #270 from probins/argparsercenter

Make options.center compatible with permalink.

lib/OpenLayers/Map.js

@@ -628,9 +628,9 @@ OpenLayers.Map = OpenLayers.Class({
              * be properly set below.
              */
             delete this.center;
-            this.addLayers(options.layers);        
+            this.addLayers(options.layers);
             // set center (and optionally zoom)
-            if (options.center) {
+            if (options.center && !this.getCenter()) {
                 // zoom can be undefined here
                 this.setCenter(options.center, options.zoom);
             }