Replace busmaps/gtfs.pro links with upstream url

[jbruechert]

These are just mirrored / postprocessed feeds.

Unfortunately we are starting to get blocked by their DDOS protection.

The source link can be found on their website. For example for De Lijn, the link is mentioned under "This source data was downloaded from this link."

[Altonss]

To replace gtfs.pro in Sweden, we could use the official feed from https://www.trafiklab.se/api/gtfs-datasets/overview/ (though it seems to need an API key), and maybe have GTFS Sweden 3 and GTFS Sverige 2 to get the best of both?

Edit: I'm sorry, I didn't see that is being discussed in #125 :)