Merge pull request #293 from jamesrhurst/master

Fixed typo in README
Implemented DNS query
Merge pull request #294 from jamesrhurst/dns-query

Implemented DNS query
Implemented modular inverse
Forgot #[cfg(not(test))] for DNS query main
Merge pull request #296 from jamesrhurst/dns-query-fix

Forgot #[cfg(not(test))] for DNS query main
Merge pull request #295 from gsingh93/modinv

Implemented modular inverse