Fix train announcements at endpoints

[lizzard]

If you're in an endpoint station and the trains are moving towards you, they say that there's x minutes till the endpoint, but that doesn't make a lot of sense since you don't want to go there; you are already there. Maybe refine things so that in this situation, you get a message that it's X minutes till it arrives in that endpoint and then will be north/south-bound to the other endpoint.