Coal Power Plant

Adds a Coal Power Plant industry that accepts coal and produces no cargo - a coal sink that earns transport income like any other delivery. Machines can be delivered as an optional productivity booster. Built from vanilla TF3 parts: boiler and turbine halls, twin 49 m stacks, coal bunkers, a cooling-water tank and ash silos around the coal unloading terminal. Generates on new maps that have coal mines, usually somewhat close to towns, and can be placed manually in sandbox.