Initial Routing support!

There was a lot I had to implement for this. After thinking about how you can actually enter the two Stations, I decided to just put a Search-Button on the Departure List and reuse most of the existing UI. It also was not easy to adapt the Data-Models because Transitous also returns Walking-Instructions as Trips.
Let me repeat that: AS TRIPS. In which world should a Walk between two nearby stations be in the same array as the normal Trips?!

Anyways, this is far from completion as you can’t actually see how you are supposed to travel.