Merge branch 'stable-3.1' into 'stable-3.1'

install/sql/incremental/upd_dev_collection.sql

install/sql/ispconfig3.sql

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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