Add muxing trait and architecture

example/examples/echo-server.rs

@@ -66,7 +66,7 @@ fn main() {
     let future = with_echo.listen_on(swarm::multiaddr::Multiaddr::new("/ip4/0.0.0.0/tcp/10333").unwrap())
         .map_err(|_| panic!())
         .unwrap()
-        .for_each(|socket| {
+        .for_each(|(socket, _)| {
             loop_fn(socket, |socket| {
                 socket.into_future()
                     .map_err(|(err, _)| err)