Fuel Gas for settlement

Gas used in houses for heating food and cooking, and it is also used for heating homes at cold seasons and water heating. So I suggest to either add a second tier for settlement water facility with an input port for Fuel Gas, or a new settlement attachment - Central Heating Facility, providing Heating service for extra unity income. 'Cuz our hard-laboring settlers deserve a hot shower after a long shift!

And then add a third level of diesel as well, because even the settlements have cars.

This could make the "cold" disease appear less often.