Merge branch 'stable-3.1'

install/dist/tpl/gentoo/amavisd-ispconfig.conf.master

install/tpl/amavisd_user_config.master

install/tpl/fedora_amavisd_conf.master

install/tpl/opensuse_amavisd_conf.master

interface/lib/classes/db_mysql.inc.php

interface/lib/lang/nl.lng

interface/web/client/lib/lang/nl.lng

interface/web/client/lib/lang/nl_client_del.lng

interface/web/client/lib/lang/nl_client_message.lng

interface/web/client/lib/lang/nl_clients_list.lng

interface/web/client/lib/lang/nl_domain.lng

interface/web/client/lib/lang/nl_domain_list.lng

interface/web/client/lib/lang/nl_reseller.lng

interface/web/client/lib/lang/nl_resellers_list.lng

interface/web/dashboard/dashlets/templates/databasequota.htm

interface/web/dashboard/dashlets/templates/limits.htm

interface/web/dashboard/dashlets/templates/mailquota.htm

interface/web/dashboard/dashlets/templates/quota.htm

interface/web/dashboard/lib/lang/nl_dashlet_customer.lng

...rface/web/dashboard/lib/lang/nl_dashlet_databasequota.lng