v1.3.0

• Add PromiseContext.isExecutingNow (TWLPromiseContext.isExecutingNow in Obj-C) that returns true if accessed from within a callback registered with .nowOr(_:) and executing synchronously, or false otherwise. If accessed from within a callback (or Promise.init(on:_:)) registered with .immediate and running synchronously, it inherits the surrounding scope's PromiseContext.isExecutingNow flag. This is intended to allow Promise(on: .immediate, { … }) to query the surrounding scope's flag (#53).
• Add convenience methods to Obj-C for doing then+catch together, as this is a common pattern and chaining Obj-C methods is a little awkward (#45).
• Change Promise.timeout's default context to .nowOr(.auto) for the Error overload as well.
• Change the behavior of Promise.timeout(on:delay:) when the delay is less than or equal to zero, the context is .immediate or .nowOr(_:), and the upstream promise hasn't resolved yet. Previously the timeout would occur asynchronously and the upstream promise would get a chance to race the timeout. With the new behavior the timeout occurs synchronously (#49).