Merge branch 'stable-3.1' of git.ispconfig.org:ispconfig/ispconfig3 into stable-3.1

interface/lib/classes/db_mysql.inc.php

interface/lib/classes/plugin_listview.inc.php

interface/lib/lang/br.lng

interface/lib/lang/tr.lng

interface/web/admin/form/users.tform.php

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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