Aiomqtt

I've tested the library for production use at SBT Instruments. This uncovered a bunch of bugs and missing features that I've adressed in this release. We are approaching a 1.0.0 release. Let me know if you want something changed before that via the issue tracker on GitHub.

Added

- Add support for MQTTv5.
- Add `will` keyword argument to `Client`.
- Add `MqttConnectError` with specific error messages for connection failures.
- Add `Client.id` property that returns the client ID (or `None` if the client ID was not specified during construction).

Fixed

- Fix unhandled exception error.
- Fix "Task was destroyed but it is pending" error.
- Fix compatibility with `asyncqt`'s event loop.
- Fix race condition in `Client.connect` that raised an `AttributeError`.
- Fix "[asyncio] Future exception was never retrieved" debug message.
- Fix support for python 3.6. Contributed by [Derrick Lyndon Pallas (pallas)](https://github.com/pallas) in [#12](https://github.com/sbtinstruments/asyncio-mqtt/pull/12)

Changed

- No longer logs exception in `Client.__aexit__`. It's perfectly valid to exit due to, e.g., `asyncio.CancelledError` so let's not treat it as an error.

Added

- Add support for python 3.6. Contributed by [Derrick Lyndon Pallas (pallas)](https://github.com/pallas) in [#7](https://github.com/sbtinstruments/asyncio-mqtt/pull/7) (1/2).
- Add `client_id` and `tls_context` keyword arguments to the `Client` constructor. Contributed by [Derrick Lyndon Pallas (pallas)](https://github.com/pallas) in [#7](https://github.com/sbtinstruments/asyncio-mqtt/pull/7) (2/2).
- Add `timeout` keyword argument to both `Client.connect` and `Client.disconnect`. Default value of `10` seconds (like the other functions).

Changed

- Propagate disconnection errors to subscribers. This enables user code to detect if a disconnect occurs. E.g., due to network errors.

Changed

- **BREAKING CHANGE:** Forward the [MQTTMessage](https://github.com/eclipse/paho.mqtt.python/blob/1eec03edf39128e461e6729694cf5d7c1959e5e4/src/paho/mqtt/client.py#L355)
class from paho-mqtt instead of just the `payload`. This applies to both
`Client.filtered_messages` and `Client.unfiltered_messages`.

This way, user code not only gets the message `payload` but also the `topic`, `qos` level, `retain` flag, etc.

Contributed by [Matthew Bradbury (MBradbury)](https://github.com/MBradbury) in [#3](https://github.com/sbtinstruments/asyncio-mqtt/pull/3).

Added

- Add `username` and `password` keyword arguments to the `Client` constructor. Contributed by [gluap](https://github.com/gluap) in [#1](https://github.com/sbtinstruments/asyncio-mqtt/pull/1).

Fixed

- Fix log message context for `Client.filtered_messages`.

Fixed

- Fix regression with the `Client._wait_for` helper method introduced in the latest release.