Allow subnet for xfer and also notify (#3122)

interface/lib/classes/validate_dns.inc.php

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

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

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

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

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

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

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

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

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

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

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

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

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

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