0.3.5

• Added StreamExt::flat_map.
• Added StreamExt::ready_chunks.
• Added *_unpin methods to SinkExt.
• Added a cancellation() future to oneshot::Sender.
• Added reunite method to ReadHalf and WriteHalf.
• Added Extend implementations for Futures(Un)Ordered and SelectAll.
• Added support for reexporting the join! and select! macros.
• Added no_std support for the pending! and poll! macros.
• Added Send and Sync support for AssertUnmoved.
• Fixed a bug where Shared wasn't relinquishing control to the executor.
• Removed the Send bound on the output of RemoteHandle.
• Relaxed bounds on FuturesUnordered.
• Reorganized internal tests to work under different --features.
• Reorganized the bounds on StreamExt::forward.
• Removed and replaced a large amount of internal unsafe.