gtfstidy: Add support for swapping coordinates

[jbruechert]

Implement a check in gtfstidy that finds unrealistic goordinates (swapped longitude and latitude), and corrects them.

This could be done like the following:

• If the speed between two stops is MUCH larger then the overall average speed
• Note the second stop
• If the speed between the second and the next stop is unrealistic again, swap coordinates for the second stop

[1Maxnet1]

I think this is not in the scope of gtfstidy:

Output feeds are semantically equivalent to the input feed.

But I thought about to create a similar tool, which can apply different fixes like:

• swapping the coordinates
• override coordinates with the ones from OSM (e.g. if the stop in the dataset has set the coordinates to (0,0))
• ...

This would allow to be extended/configured to fix all kind of automatically fixable issues in the datasets.

[felixguendling]

We had functionality like this in MOTIS before.

motis-project/motis@d90e87a

But it sometimes made things even worse, so I removed it.

Edit 1: It's easier to reason about strange things popping up in the search UI if MOTIS doesn't do too much data fixing and interpretation.

Edit 2: But maybe it makes sense to keep the problem detection part of this code so the MOTIS writes logs that point to dubious trip IDs.

[jbruechert]

Output feeds are semantically equivalent to the input feed.

At least with the --fix option that is already not the case, so I'd just ask upstream before starting to work on it.