journeys(): support multiple via points

[yu-re-ka]

I don't know the api format needed for this, but it should be possible to enter multiple via points

[derhuerst]

We could change the code to handle opt.via being an array. This is the current implementation:

https://github.com/public-transport/hafas-client/blob/9c10a1765fbc737c58b4bbed237a22394a0cf0fb/index.js#L144

[fightforlife]

should multiple via points in an array handled as AND (the journey has to go through all via points) or OR (Journeys can go through either point)

[derhuerst]

Note sure! Do we know if HAFAS supports both? Would be great if someone could investigate this!