Real Feel Temp

Provides the real feel temp based on humidity and current temprature.

Uses cond.feelsLikeTemperature first (existing behavior). If that is null, falls back to cond.temperature and computes: Heat index when hot/humid (relativeHumidity available, temp greater than equal to 80F, RH greater than equal to 40%). Wind chill when cold/windy (windSpeed available, temp less than equal to 50F, wind greater than 3 mph). Otherwise just uses ambient temperature.