Review MOTIS trip display name logic

[jbruechert]

In some areas we end up without any name for a trip (MAV) and in some we end up with very weird looking names that are likely not what is visible on a station departure board (various trains in France).
This could be an issue in the feeds, or the logic in MOTIS can be improved. There are various strings to choose from (at least trip_short_name, route_short_name and route_long_name).

[Altonss]

Some names are really weird, for example the new Ouigo Bruxelles-Paris. Probably an error in the feed :/

[Altonss]

Similar upstream discussion here: motis-project/motis#691

[jbruechert]

Relevant code seems to be here: https://github.com/motis-project/nigiri/blob/master/src/loader/gtfs/trip.cc#L191

Overall the existing logic seems to be made for Germany and probably needs improvements for other places.
In particular, I suspect combining route and trip name creates weird results.

For example for TGVs, we get things like "081B 5358". Probably just the trip name (second) would be what you'd expect, right?

[jbruechert]

For Austria trip_short_name is also the right thing (for example EC 113) but we get "D7" which is a route name that means nothing to most people.

After all we likely get the best results when reverse-engineering google maps behaviour and copying it, as that is what people test their feeds with.

[jbruechert]

I started to improve it a bit here: motis-project/nigiri#163

I'm very interested in opinions / conventions from other regions to make this as correct as possible.