Vendor dependencies for 0.3.0 release

vendor/windows-future/README.md

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+## Windows async types
+
+The [windows-future](https://crates.io/crates/windows-future) crate provides stock async support for Windows APIs.
+
+* [Getting started](https://kennykerr.ca/rust-getting-started/)
+* [Samples](https://github.com/microsoft/windows-rs/tree/master/crates/samples)
+* [Releases](https://github.com/microsoft/windows-rs/releases)
+
+Start by adding the following to your Cargo.toml file:
+
+```toml
+[dependencies.windows-future]
+version = "0.3"
+```
+
+Use the Windows async types as needed:
+
+```rust
+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);
+```