perf(h1): improve parsing and encoding of http1 messages

src/client/conn.rs

@@ -531,7 +531,7 @@ impl<T, B, R> Future for HandshakeInner<T, B, R>
 where
     T: AsyncRead + AsyncWrite + Send + 'static,
     B: Payload,
-    R: proto::Http1Transaction<
+    R: proto::h1::Http1Transaction<
         Incoming=StatusCode,
         Outgoing=proto::RequestLine,
     >,

src/client/mod.rs

@@ -193,7 +193,6 @@ where C: Connect + Sync + 'static,
             Version::HTTP_11 => (),
             other => {
                 error!("Request has unsupported version \"{:?}\"", other);
-                //TODO: replace this with a proper variant
                 return ResponseFuture::new(Box::new(future::err(::Error::new_user_unsupported_version())));
             }
         }