Revert "fixes" from StyleCI

These were intended, to simplify getting started or changing things in
the base skeleton.

StyleCI has now been disabled for this repository.

extend.php

@@ -9,6 +9,8 @@
  * file that was distributed with this source code.
  */
 
+use Flarum\Extend;
+
 return [
     // Register extenders here to customize your forum!
 ];