Rust command line client

Looking great @jcassee! Like what you’ve done so far. We’re actually working on some improvements to the API which should streamline some parts of the client / reduce what you need to do yourself, so keep an eye out for that. And if there are other things you’d like to see that would make building a client lib easier / better, of course let us know.

With regards to naming, feel free to release it as a crate. If and when there is a Supernotes official Rust lib, I’m sure we can figure it out then!