Update prepare() method on Action subclasses.

Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::prepare() should be compatible with
Action::prepare(array $args = Array)

Ref. #190

plugins/DirectMessage/lib/mailboxaction.php

@@ -46,7 +46,7 @@ class MailboxAction extends Action
 {
     var $page = null;
 
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);