[Feature Request] Get WU RainBool from precipRate
As WU doesn't provide a `rainBool` value couldn't we use `precipRate`? Like when `precipRate` > 0.00 then `rainBool = true`and `when 0.00 then rainBool = false`. Also we could add a threshold option when `rainBool` is triggered from `precipRate`.

Also there seems to be a public API key that can be used without registration. See https://www.loxwiki.eu/display/LOX/Wunderground-Anbindung+ohne+API-Key

