timer: move tokio-timer into tokio crate (#1674)

A step towards collapsing Tokio sub crates into a single `tokio`
crate (#1318).

The `timer` implementation is now provided by the main `tokio` crate.
The `timer` functionality may still be excluded from the build by
skipping the `timer` feature flag.

tokio-test/src/io.rs

@@ -16,6 +16,11 @@
 //! [`AsyncRead`]: tokio_io::AsyncRead
 //! [`AsyncWrite`]: tokio_io::AsyncWrite
 
+use tokio::timer::{clock, timer, Delay};
+use tokio_io::{AsyncRead, AsyncWrite, Buf};
+use tokio_sync::mpsc;
+
+use futures_core::ready;
 use std::collections::VecDeque;
 use std::future::Future;
 use std::pin::Pin;
@@ -23,11 +28,6 @@ use std::task::{self, Poll, Waker};
 use std::time::{Duration, Instant};
 use std::{cmp, io};
 
-use futures_core::ready;
-use tokio_io::{AsyncRead, AsyncWrite, Buf};
-use tokio_sync::mpsc;
-use tokio_timer::{clock, timer, Delay};
-
 /// An I/O object that follows a predefined script.
 ///
 /// This value is created by `Builder` and implements `AsyncRead` + `AsyncWrite`. It
@@ -268,42 +268,6 @@ impl Inner {
     }
 }
 
-/*
-impl io::Read for Mock {
-    fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
-        if self.is_async() {
-            tokio::async_read(self, dst)
-        } else {
-            self.sync_read(dst)
-        }
-    }
-}
-
-impl io::Write for Mock {
-    fn write(&mut self, src: &[u8]) -> io::Result<usize> {
-        if self.is_async() {
-            tokio::async_write(self, src)
-        } else {
-            self.sync_write(src)
-        }
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        Ok(())
-    }
-}
-*/
-
-/*
-use self::futures::{Future, Stream, Poll, Async};
-use self::futures::sync::mpsc;
-use self::futures::task::{self, Task};
-use self::tokio_io::{AsyncRead, AsyncWrite};
-use self::tokio_timer::{Timer, Sleep};
-
-use std::io;
-*/
-
 // ===== impl Inner =====
 
 impl Mock {