A Rust implementation of MessagePack-RPC based on tokio.

• Support all the features described in MessagePack-RPC specifications.
• Support for endpoints that act both as client and server. This is not part of the specification, but is a relatively common use of MessagePack-RPC.
• Support any transport layer.

• client.rs: a simple client
• server.rs: a simple server
• Ping Pong: an example with endpoints that are both client and server.