Generic iuse function for weather reading devices

I changed the iuse function that read weather to be more generic. If an item is flagged and has the action "weather_reader", it will read the weather. For example, when thermometers are added, it will only have the one flag and thus only display that one piece of information, but still use the same generic function! yay!
I wasn't sure what that was doing there--looked like a substantive change.  I'm gonna hold on this thanks to feature freeze, but thanks for the update.