Rename errorpage() to util_show_error_page() and move util_show_error_page() into include/util.php

admin/adminMaintainers.php

@@ -17,7 +17,7 @@ $aClean['maintainerId'] = makeSafe($_REQUEST['maintainerId']);
 // deny access if not logged in
 if(!$_SESSION['current']->hasPriv("admin"))
 {
-    errorpage("Insufficient privileges.");
+    util_show_error_page("Insufficient privileges.");
     exit;
 }