Function map_model::make::traffic_signals::synchronize

pub fn synchronize(map: &mut Map)

Simple second-pass after generating all signals. Find pairs of traffic signals very close to each other with 2 stages each, see if the primary movement of the first stages lead to each other, and flip the order of stages if not. This is often wrong when the most common movement is actually turning left then going straight (near Mercer for example), but not sure how we could know that without demand data.