Changed windchill model [WIP]

I've decided to change the windchill model based on this forum post : http://smf.cataclysmdda.com/index.php?topic=8002.msg184741#msg184741

There is a bug in my code that I am blind to : windchill always turns "1" ??? I don't understand why. Hoping someone with C++ experience could point it out.

This PR also adds a debug item, the pocket meteorologist, which simply messages the player the absolute temp, pressure and humidity. Once the windchill=1 bug is fixed, I can remove the item if necessary.