message: transport: Export ConnectionEvent enum at toplevel
  Part of API that should be easy to import.
diff: @@ -19,7 +19,7 @@ pub mod send_stream;
  mod tparams;
  mod tracking;
  -pub use self::connection::{Connection, Datagram, State};
  +pub use self::connection::{Connection, ConnectionEvent, Datagram, State};
  pub use recv_stream::Recvable;
  pub use send_stream::Sendable;
  