PHP/Compat

* remove sources of deprecation warnings. Mostly dynamic creation of object properties.
 * some string function no longer accept null as string

includes/types/arenateam.class.php

@@ -10,6 +10,8 @@ class ArenaTeamList extends BaseType
 
     private $rankOrder = [];
 
+    public static $contribute = CONTRIBUTE_NONE;
+
     public function getListviewData()
     {
         $data = [];