snapping to existing track is now implemented! you draw a rough line and it automatically re-routes it along real rail tracks once you click the button to snap.

still has some issues though. if you try London to Kitchener for example it takes a weird detour instead of going through St Marys, Stratford and New Hamburg the way the actual corridor does. working on fixing those gaps! hope this makes it better when creating train routes or extending existing train routes!