Warm sunlight, radiative cooling into space

[Coolthulhu]

It seems that at the moment, sunlight doesn't heat anything up. At least not enough to be noticeable. Solar panels could be considered an exception, but they actually heat up from any light, including shinebugs.

A simple way to implement warm sunlight and radiative cooling would look like this:

• If a non-transparent tile is in direct sunlight, it gets some W of heating, scaling with light intensity
• If a non-transparent tile is "visible" from the top of the map, it loses some W of heat, scaling with tile's temperature

This could be used for cooling and possibly actually renewable steam power.