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/random_image/main.php

@@ -75,4 +75,11 @@ class RandomImage extends Extension
             }
         }
     }
+
+    public function onPageSubNavBuilding(PageSubNavBuildingEvent $event)
+    {
+        if($event->parent=="posts") {
+            $event->add_nav_link("posts_random", new Link('random_image/view'), "Random Image");
+        }
+    }
 }