This allows overriding of the connect() method by a subclass as per the
included examples: `example_lwt_robust.py` and `example_resubscribe_robust.py`.
Co-authored by: Ian Cotter-Llewellyn <ian_llewellyn@hotmail.com>
Date: Thu May 25 11:42:20 2023 +0100
After `reconnect()`, MQTTClient.socket is blocking by default, and
check_msg() can block. This commit aims to fix that behaviour by
reimplementing `check_msg()` for umqtt.robust and setting the socket to
non-blocking.
Fixes issue #192.
puuu