Improve device discovery.

[sweebee]

I have a simple weatherstation. Autodiscovey found 3 devices, but only 1 is correct. Is it possible to look also at the variables like the the temperature and humidity? One wrong device showed me -190 degrees. So if a device shows numbers like lower than -50 or higher than +50, don't show them in the discovery.

Maybe this is possible for more devices. I tested domoticz once and it always showed me the right one.

[sweebee]

And maybe its also better to only accept 'ON' messages for discovery of switch devices. Other house automation applications also do this.