We miss explicit equal comparator registration for types held as variants
inside Reservation objects. Ideally this is something done in the library
eventually, but it's not straightforward to do early enough there, in
particular in static builds. So we do this here for now.

This fixes live data updates triggering reservation changes
unconditionally, and thus everything that follows from there.

The screenshots in issue #29 show this happening, and it's obviously
pointless given unbound tickets have no exact times associated yet.

This also removes the last traces of KPublicTransport::Departure, and
extends the unit testing of LiveDataManager.

Less duplicated code, and less code that is hardcoded to train
reservations.