Checking timestamps for stopovers

[MrKrisKrisu]

Here's a reminder that the removal of the check for departure time equality caused new issues on trips that contain the the same stopover multiple times, as I mentioned in #2407 (comment) using my wrong account. I won't repeat the description, furthermore I don't have the capacity to create a new issue or fix it myself. I just wanted to put this comment here as a reminder since I feel it might have been overseen, especially as github hides it behind a resolved review.

Originally posted by @d3d9 in #2407 (comment)

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@d3d9 do you have some input here before we are merging this as you worked on this snipped before? Thank you for notifying me. I'm afraid I wasn't able to respond earlier.
I think the departure time check was there for a good reason. On my first attempt testing out the new code, I could notice how, also using the Gesundbrunnen example, with a train that is passing it the second time, I get shown the stopovers before the second Gesundbrunnen one. Checking in fails ("Departure time must be before arrival time"), but we should prevent the wrong stopovers being displayed.
Instead of removing the departure time check, it should be kept and fixed with respect to timezones.

Originally posted by @kevin-a-vt in #2407 (comment)