Add "Train Nickname" Tag

[ChillLP]

A Tag to add the name of the Train/loco rather than the Baureihe would be nice, as i classify my trains by BR, and Sometimes i would Like to add the Taufnamen

[jheubuch]

I'd like to clarify this with the @Traewelling team, until documented, I'll keep this as blocked.

[ChillLP]

Ref: Traewelling/traewelling#2067

[MrKrisKrisu]

I'd like to clarify this with the @Traewelling team, until documented, I'll keep this as blocked.

Status tags are not required to have documented trwl:__ value. You can use your own tags with your prefix as well.

[jheubuch]

I'd like to clarify this with the @Traewelling team, until documented, I'll keep this as blocked.

Status tags are not required to have documented trwl:__ value. You can use your own tags with your prefix as well.

Yes I know, but for interoperability reasons, I think it would be best if everywhere it's the same :D

[jheubuch]

Implemented with trwl:vehicle_number