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

install/lib/installer_base.lib.php

interface/lib/classes/db_mysql.inc.php

interface/lib/classes/remoting_lib.inc.php

interface/web/admin/server_config_edit.php

interface/web/admin/templates/server_config_cron_edit.htm

interface/web/admin/templates/server_config_dns_edit.htm

interface/web/admin/templates/server_config_fastcgi_edit.htm

interface/web/admin/templates/server_config_getmail_edit.htm

interface/web/admin/templates/server_config_jailkit_edit.htm

interface/web/admin/templates/server_config_mail_edit.htm

interface/web/admin/templates/server_config_rescue_edit.htm

interface/web/admin/templates/server_config_server_edit.htm

interface/web/admin/templates/server_config_ufw_edit.htm

interface/web/admin/templates/server_config_vlogger_edit.htm

interface/web/admin/templates/server_config_web_edit.htm

interface/web/admin/templates/server_config_xmpp_edit.htm

interface/web/mail/form/mail_transport.tform.php

interface/web/monitor/lib/lang/ar.lng

interface/web/monitor/lib/lang/bg.lng

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