chore: Fix examples not working with `cargo run` (#998)

* chore: Fix examples not working with `cargo run`

## Motivation

PR #991 moved the `tokio` crate to its own subdirectory, but did not
move the `examples` directory into `tokio/examples`. While attempting to
use the examples for testing another change, I noticed that #991 had
broken the ability to use `cargo run`, as the examples were no longer
considered part of a crate that cargo was aware of:

```
tokio on master [$] via 🦀v1.33.0 at ☸️ aks-eliza-dev
➜  cargo run --example chat
error: no example target named `chat`

Did you mean `echo`?
```

## Solution

This branch moves the examples into the `tokio` directory, so cargo is
now once again aware of them:

```
tokio on eliza/fix-examples [$] via 🦀v1.33.0 at ☸️ aks-eliza-dev
➜  cargo run --example chat
   Compiling tokio-executor v0.1.7 (/Users/eliza/Code/tokio/tokio-executor)
   Compiling tokio-reactor v0.1.9
   Compiling tokio-threadpool v0.1.13
   Compiling tokio-current-thread v0.1.6
   Compiling tokio-timer v0.2.10
   Compiling tokio-uds v0.2.5
   Compiling tokio-udp v0.1.3
   Compiling tokio-tcp v0.1.3
   Compiling tokio-fs v0.1.6
   Compiling tokio v0.1.18 (/Users/eliza/Code/tokio/tokio)
    Finished dev [unoptimized + debuginfo] target(s) in 7.04s
     Running `target/debug/examples/chat`
server running on localhost:6142
```

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

1 files changed, 0 insertions, 115 deletions

diff --git a/examples/echo.rs b/examples/echo.rs
deleted file mode 100644
index 45f808f8..00000000
--- a/examples/echo.rs
+++ /dev/null
@@ -1,115 +0,0 @@
-//! A "hello world" echo server with Tokio
-//!
-//! This server will create a TCP listener, accept connections in a loop, and
-//! write back everything that's read off of each TCP connection.
-//!
-//! Because the Tokio runtime uses a thread pool, each TCP connection is
-//! processed concurrently with all other TCP connections across multiple
-//! threads.
-//!
-//! To see this server in action, you can run this in one terminal:
-//!
-//!     cargo run --example echo
-//!
-//! and in another terminal you can run:
-//!
-//!     cargo run --example connect 127.0.0.1:8080
-//!
-//! Each line you type in to the `connect` terminal should be echo'd back to
-//! you! If you open up multiple terminals running the `connect` example you
-//! should be able to see them all make progress simultaneously.
-
-#![deny(warnings)]
-
-extern crate tokio;
-
-use tokio::io;
-use tokio::net::TcpListener;
-use tokio::prelude::*;
-
-use std::env;
-use std::net::SocketAddr;
-
-fn main() -> Result<(), Box<std::error::Error>> {
-    // Allow passing an address to listen on as the first argument of this
-    // program, but otherwise we'll just set up our TCP listener on
-    // 127.0.0.1:8080 for connections.
-    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
-    let addr = addr.parse::<SocketAddr>()?;
-
-    // Next up we create a TCP listener which will listen for incoming
-    // connections. This TCP listener is bound to the address we determined
-    // above and must be associated with an event loop, so we pass in a handle
-    // to our event loop. After the socket's created we inform that we're ready
-    // to go and start accepting connections.
-    let socket = TcpListener::bind(&addr)?;
-    println!("Listening on: {}", addr);
-
-    // Here we convert the `TcpListener` to a stream of incoming connections
-    // with the `incoming` method. We then define how to process each element in
-    // the stream with the `for_each` method.
-    //
-    // This combinator, defined on the `Stream` trait, will allow us to define a
-    // computation to happen for all items on the stream (in this case TCP
-    // connections made to the server).  The return value of the `for_each`
-    // method is itself a future representing processing the entire stream of
-    // connections, and ends up being our server.
-    let done = socket
-        .incoming()
-        .map_err(|e| println!("failed to accept socket; error = {:?}", e))
-        .for_each(move |socket| {
-            // Once we're inside this closure this represents an accepted client
-            // from our server. The `socket` is the client connection (similar to
-            // how the standard library operates).
-            //
-            // We just want to copy all data read from the socket back onto the
-            // socket itself (e.g. "echo"). We can use the standard `io::copy`
-            // combinator in the `tokio-core` crate to do precisely this!
-            //
-            // The `copy` function takes two arguments, where to read from and where
-            // to write to. We only have one argument, though, with `socket`.
-            // Luckily there's a method, `Io::split`, which will split an Read/Write
-            // stream into its two halves. This operation allows us to work with
-            // each stream independently, such as pass them as two arguments to the
-            // `copy` function.
-            //
-            // The `copy` function then returns a future, and this future will be
-            // resolved when the copying operation is complete, resolving to the
-            // amount of data that was copied.
-            let (reader, writer) = socket.split();
-            let amt = io::copy(reader, writer);
-
-            // After our copy operation is complete we just print out some helpful
-            // information.
-            let msg = amt.then(move |result| {
-                match result {
-                    Ok((amt, _, _)) => println!("wrote {} bytes", amt),
-                    Err(e) => println!("error: {}", e),
-                }
-
-                Ok(())
-            });
-
-            // And this is where much of the magic of this server happens. We
-            // crucially want all clients to make progress concurrently, rather than
-            // blocking one on completion of another. To achieve this we use the
-            // `tokio::spawn` function to execute the work in the background.
-            //
-            // This function will transfer ownership of the future (`msg` in this
-            // case) to the Tokio runtime thread pool that. The thread pool will
-            // drive the future to completion.
-            //
-            // Essentially here we're executing a new task to run concurrently,
-            // which will allow all of our clients to be processed concurrently.
-            tokio::spawn(msg)
-        });
-
-    // And finally now that we've define what our server is, we run it!
-    //
-    // This starts the Tokio runtime, spawns the server task, and blocks the
-    // current thread until all tasks complete execution. Since the `done` task
-    // never completes (it just keeps accepting sockets), `tokio::run` blocks
-    // forever (until ctrl-c is pressed).
-    tokio::run(done);
-    Ok(())
-}