Merge branch 'stable-3.1'

TODO.txt

install/lib/installer_base.lib.php

install/sql/incremental/upd_dev_collection.sql

install/sql/ispconfig3.sql

install/tpl/named.conf.options.master

interface/web/dns/dns_ds_edit.php

interface/web/dns/dns_loc_edit.php

interface/web/dns/dns_tlsa_edit.php

interface/web/dns/form/dns_ds.tform.php

interface/web/dns/form/dns_loc.tform.php

interface/web/dns/form/dns_soa.tform.php

interface/web/dns/form/dns_tlsa.tform.php

interface/web/dns/lib/lang/de_dns_ds.lng

interface/web/dns/lib/lang/de_dns_loc.lng

interface/web/dns/lib/lang/de_dns_soa.lng

interface/web/dns/lib/lang/de_dns_spf.lng

interface/web/dns/lib/lang/de_dns_tlsa.lng

interface/web/dns/lib/lang/en_dns_ds.lng

interface/web/dns/lib/lang/en_dns_loc.lng

interface/web/dns/lib/lang/en_dns_soa.lng