Release 3.1.0 · ReactiveCocoa/ReactiveSwift

This is the first release of ReactiveSwift 3.1. It supports Swift 3.2 and Swift 4.0.

Bugfix

Fixed a scenario of downstream interruptions being dropped. (#577, kudos to @andersio)

Manual interruption of time shifted producers, including delay, observe(on:), throttle, debounce and lazyMap, should discard outstanding events at best effort ASAP.

But in ReactiveSwift 2.0 to 3.0, the manual interruption is ignored if the upstream producer has terminated. For example:
```
// Completed upstream + `delay`.
SignalProducer.empty
    .delay(10.0, on: QueueScheduler.main)
    .startWithCompleted { print("The producer should have been interrupted!") }
    .dispose()

// Console(t+10): The producer should have been interrupted!
```
The expected behavior has now been restored.

Please note that, since ReactiveSwift 2.0, while the interruption is handled immediately, the interrupted event delivery is not synchronous — it generally respects the closest asynchronous operator applied, and delivers on that scheduler.
Fixed schedule(after:interval:leeway:) being cancelled when the returned Disposable is not retained. (#584, kudos to @jjoelson)

The issue affects only direct use of QueueScheduler. SignalProducer.timer is not affected.

SignalProducer.concat now has an overload that accepts an error. (#564, kudos to @nmccann)