- Add documentation with examples to API items
- Re-export types that the public API uses
- Add blocking client API
- Fix parsing key constraints
- Split `Message` into `Request` and `Response`
- Expose `Unparsed`
- Relicense the library to MIT/Apache 2.0
- Document vast majority of protocol messages
- Add SSH_AGENT_EXTENSION_RESPONSE to implement
  `draft-miller-ssh-agent-14`
- Move `handle_socket` out of the `Session` trait
- Add `service_binding::Stream` support
- Add `verify_signature()` method to `SessionBind` extension message
  struct
- Add numerous examples
- Use `secrecy` crate to protect PINs from accidental leaks

Thanks to @baloo, @jcspencer, @overhacked and @robin-nitrokey for
their contributions!