Make sure unused layers are hidden

When parsing an old style layer configuration string, make sure any
layer which isn't active is marked as invisible so that we don't
include it when generating permalinks. Fixes #3773.

public/javascripts/map.js

@@ -251,6 +251,8 @@ function setMapLayers(layerConfig) {
 
          if (c == "B") {
             map.setBaseLayer(layers[i]);
+         } else {
+            map.layers[i].setVisibility(false);
          }
       }
    } else {