Support translations.txt

Translations.txt is an extension containing the translations of (mainly) stops. The format is: 
````
trans_id,lang,translation
Ingelmunster,fr,Ingelmunster
Ingelmunster,nl,Ingelmunster
Ingelmunster,de,Ingelmunster
Ingelmunster,en,Ingelmunster
````

Having support for this would greatly benefit itinero-transit