Crate windows_future Copy item path

[dependencies.windows-future]
version = "0.3"

use windows_future::*;

// This result will be available immediately.
let ready = IAsyncOperation::ready(Ok(123));
assert_eq!(ready.join().unwrap(), 123);

let ready = IAsyncOperation::spawn(|| {
    // Some lengthy operation goes here...
    Ok(456)
});

assert_eq!(ready.join().unwrap(), 456);