Fix add hidden option INVOICE_DEFAULT_UNPAYED_SORT_ORDER to be able to

provide backward compatibility with old behaviour.

htdocs/compta/facture/list.php

@@ -83,6 +83,7 @@ if ($page == -1) {
     $page = 0;
 }
 $offset = $limit * $page;
+if (! $sortorder && ! empty($conf->global->INVOICE_DEFAULT_UNPAYED_SORT_ORDER) && $search_status == 1) $sortorder=$conf->global->INVOICE_DEFAULT_UNPAYED_SORT_ORDER;
 if (! $sortorder) $sortorder='DESC';
 if (! $sortfield) $sortfield='f.datef';