[Feature Request] Add UV index

UV index could be added to details page and tooltip.

Unfortunately met.no provides UV index for JSON API (ultraviolet_index_clear_sky), but not for XML API. It means weather-plugin has to move to JSON API.

I could try to migrate, but I have to know how to use JSON in C code (which library would be preferred, etc.).

added 2. Feature label

It means weather-plugin has to move to JSON API.

It already moved to JSON API: !27 (merged), or is there something else?

Right! I didn't notice it already uses JSON for sunrise , so it simplifies things. However locationforecast still uses XML API. This issue is about to remove classic from locationforecast URL and migrate to JSON. Next step is to read ultraviolet_index_clear_sky. It's in cb_weather_update() and parse_weather() functions.