Todo

Stop hammering whois service, maybe use mock library?
Add append (non-domain hack) mode; also allow 'website.com' for example
Add internet slang wordlist
Use terms properly (domain, suffix)
Add Public Suffix List checking (https://en.wikipedia.org/wiki/Public_Suffix_List, https://publicsuffix.org/list/)
Add more tests
Add output arg; save available domains to file