Implemented a nav link generating system so that extension power what shows up in the menus rather than being hard-coded in the themes.

ext/admin/main.php

@@ -108,6 +108,16 @@ class AdminPage extends Extension
         $this->theme->display_form();
     }
 
+    public function onPageSubNavBuilding(PageSubNavBuildingEvent $event)
+    {
+        global $user;
+        if($event->parent==="system") {
+            if ($user->can(Permissions::MANAGE_ADMINTOOLS)) {
+                $event->add_nav_link("admin", new Link('admin'), "Board Admin");
+            }
+        }
+    }
+
     public function onUserBlockBuilding(UserBlockBuildingEvent $event)
     {
         global $user;