Remove async_await feature (#99)

Author: taiki-e

README.md

@@ -69,8 +69,6 @@ asynchronous software.
 ## Examples
 __UDP Echo Server__
 ```rust
-#![feature(async_await)]
-
 use runtime::net::UdpSocket;
 
 #[runtime::main]

benches/baseline.rs

@@ -1,4 +1,4 @@
-#![feature(test, async_await)]
+#![feature(test)]
 
 extern crate test;
 

benches/native.rs

@@ -1,4 +1,4 @@
-#![feature(test, async_await)]
+#![feature(test)]
 #![warn(rust_2018_idioms)]
 
 extern crate test;

benches/tokio.rs

@@ -1,4 +1,4 @@
-#![feature(test, async_await)]
+#![feature(test)]
 #![warn(rust_2018_idioms)]
 
 extern crate test;

examples/guessing.rs

@@ -7,8 +7,6 @@
 //! $ nc localhost 8080
 //! ```
 
-#![feature(async_await)]
-
 use futures::prelude::*;
 use rand::Rng;
 use runtime::net::{TcpListener, TcpStream};

examples/hello.rs

@@ -1,5 +1,3 @@
-#![feature(async_await)]
-
 async fn say_hi() {
     println!("Hello world! 🤖");
 }

examples/tcp-client.rs

@@ -6,8 +6,6 @@
 //! $ cargo run --example tcp-echo
 //! ```
 
-#![feature(async_await)]
-
 use futures::prelude::*;
 use runtime::net::TcpStream;
 

examples/tcp-echo.rs

@@ -3,8 +3,6 @@
 //! Run the server and connect to it with `nc 127.0.0.1 8080`.
 //! The server will wait for you to enter lines of text and then echo them back.
 
-#![feature(async_await)]
-
 use futures::prelude::*;
 use runtime::net::TcpListener;
 

examples/tcp-proxy.rs

@@ -1,7 +1,5 @@
 //! A TCP proxy server. Forwards connections from port 8081 to port 8080.
 
-#![feature(async_await)]
-
 use futures::prelude::*;
 use futures::try_join;
 use runtime::net::{TcpListener, TcpStream};

examples/udp-client.rs

@@ -1,5 +1,3 @@
-#![feature(async_await)]
-
 //! UDP client.
 //!
 //! To start an echo server do: