The arwn platform was refactored to be asyncio friendly, however in
doing so one thing was missed which was explicitly telling hass when
something interesting has happened. This led to the very interesting
to debug issue that the state cards were all out of date, even though
the graphs were not.
* Fix arwn platform discover_sensors
The discover_sensors function can return either singletons or a list
of sensors. However the consumer was always expecting a list. This
fixes it to work in both cases.
* Add custom icons to arwn sensors.
This adds some custom icons for different kinds of weather sensors
that the arwn platform returns. Makes it a little easier to see what's
going on.
This adds a sensor component that builds sensors based on the arwn
project (https://github.com/sdague/arwn). This uses a 433mhz receiver
to collect weather data and publish it over mqtt in a well defined
schema, which home-assistant can display as sensors.
