IDNA support

[whatyouhide]

We might want to have a separate library that deals with IDNA and either explain to users how to use it with Mint, or have an interface in Mint that users can adapt to.

Opened this issue from #42.

[ericmj]

Closing this due to lack of activity/interest. It is not blocking 1.0 and could be built as a separate library. Let us know if you are interested in working on this and we could discuss implementation and API.