Use 24 hour clock instead of 12 hour clock

[luna-cant-code]

Even though Träwelling is used internationally, it's (afaik) just an American thing to use the 12 hour clock.

Would it be possible to switch Träwelling to the 24 hour clock? It just makes more sense, especially because almost all railways use the 24 hr clock.

[HerrLevin]

Should be closed with #4142 :)