and make the extensions match

git-svn-id: file:///home/shish/svn/shimmie2/trunk@1003 7f39781d-f577-437e-ae19-be835c7a54ca

contrib/rss_comments/main.php

@@ -6,9 +6,9 @@
  * Description: Self explanitory
  */
 
-class RSS_Comments extends Extension {
+class RSS_Comments implements Extension {
 // event handling {{{
-	public function receive_event($event) {
+	public function receive_event(Event $event) {
 		if($event instanceof PostListBuildingEvent) {
 			global $page;
 			global $config;