* Improve nat_traversal
* Remove the Box for dialing
* Improve multiaddr_to_socketaddr
* Use ? on None
* Use a proper stream for TcpListenStream
* Rustfmt
* Use tk_listen for errors on the listener
* Minor changes
* Fix concerns
* Rename Transport::RawConn to Output
* Remove AsyncRead + AsyncWrite bound on Transport::Output
* UpgradedNode now always implements Transport
* Add and tweak modifiers for Transport and ConnectionUpgrade
* Secio upgrade now returns the pubkey in its output
* Add upgrade::apply
* Add Transport::and_then
* Rework the swarm
* Rustfmt
* Fix concerns