fn get_vehicles(
person: &PersonSpec,
rng: &mut XorShiftRng
) -> (Vec<VehicleSpec>, Vec<(usize, BuildingID)>, Vec<Option<usize>>)
fn get_vehicles(
person: &PersonSpec,
rng: &mut XorShiftRng
) -> (Vec<VehicleSpec>, Vec<(usize, BuildingID)>, Vec<Option<usize>>)