* models/record.go: SRV targets are case insensitive. Downcase them.
* models/t_srv.go: Rename setTargetIntAndStrings() to setTargetSRVIntAndStrings() (makes it easier to search for /setTargetSRV/).
* pkg/js/parse_tests/021-srv.js*: SRV: Add parse_tests
* pkg/normalize/validate.go: SRV targets are hostnames, turn into FQDNs.
* Add #rtype_variations warnings for future developers