Heat up bodyparts over adjacent fires

Makes the non-sleeping survivors heat up bodyparts when there's an adjacent fire. Torso, head and legs don't get much heat unless the fire is big. Arms get more and hands get a lot, because you can get them close to fire.
Feet get only a tiny bit, unless the survivor is on a chair and then they get a lot.

Only chairs, armchairs and benches are recognized as chairs. Beds would probably catch fire from the sparks, vehicle seats would probably be hard to get in a good position.
Any other good chair-type furniture? Something non-flammable would be nice, because currently comfy campfire isn't possible.

Only the best fire is used, because one cannot extend arm over two fires at once.

Additionally I fixed a moderately severe bug with fire heat: fire heat would use max(1,max(j, k)) as distance, despite j and k often having negative values. This would make fires to the north and to the west always as hot as if they were adjacent.
`map::sees` might be useful here. It only checks the transparency of the squares via `map::trans`