added missing language string already present in default theme

cfoe

2012-05-22 0ae667e6cfdd1bcc85bacf85cd93a84f99fa88f8

 interface/web/admin/lib/lang/it_language_export.lng

New file
@@ -0,0 +1,6 @@
<?php
$wb['list_head_txt'] = 'Export language files';
$wb['language_select_txt'] = 'Select language';
$wb['btn_save_txt'] = 'Export the selected language file set';
$wb['btn_cancel_txt'] = 'Annulla';
?>