Create tokio-codec (#360)

Create a new tokio-codec crate with many of the contents of
`tokio_io::codec`.

tokio-io/src/framed_read.rs

@@ -1,3 +1,5 @@
+#![allow(deprecated)]
+
 use std::fmt;
 
 use AsyncRead;
@@ -8,10 +10,14 @@ use futures::{Async, Poll, Stream, Sink, StartSend};
 use bytes::BytesMut;
 
 /// A `Stream` of messages decoded from an `AsyncRead`.
+#[deprecated(since = "0.1.7", note = "Moved to tokio-codec")]
+#[doc(hidden)]
 pub struct FramedRead<T, D> {
     inner: FramedRead2<Fuse<T, D>>,
 }
 
+#[deprecated(since = "0.1.7", note = "Moved to tokio-codec")]
+#[doc(hidden)]
 pub struct FramedRead2<T> {
     inner: T,
     eof: bool,