Fix two bugs found by @TiuTalk

* When redirecting internal links, double-check that they actually
  are internal before doing so.
* Avoid double-adding items to the /browse mod list

src/coffee/controllers/mod_pack_controller.coffee

@@ -68,5 +68,4 @@ module.exports = class ModPackController extends BaseController
                 index += 1
 
         while @_modControllers.length > index
-            controller = @_modControllers.pop()
-            controller.$el.fadeOut duration:Duration.normal, complete:-> @remove()
+            @_modControllers.pop().remove()