Support auto conversion if field is renamed

[markusjura]

teleproto tries to auto-convert based on field names. If the input/output object has the same structure but a field name has changed in one of the objects, a customer Reader or Writer needs to be defined, e.g.

    implicit val writerDomainV3: Writer[TripModel.Offer, domain.Offer] = {
      case offer: TripModel.Offer =>
        domain.Offer(
          offer.id,
          offer.serviceAreaUuid,
          Some(SeatInfo.domainWriterV3.write(offer.seatInfo)),
          Some(Price.priceWriterV3.write(offer.price)),
          offer.priceMetadata.map(PriceMetadata.domainWriterV3.write),
          Some(NamedLocation.domainWriterV3.write(offer.origin)),
          offer.walkToPickup.map(Walk.domainWriterV3.write),
          offer.pickupStop.map(Stop.domainWriterV3.write),
          offer.pickupArea.map(StopArea.writerDomainV3.write),
          Some(TimeRange.writerV3.write(offer.pickupTimeRange)),
          offer.deliveryStop.map(Stop.domainWriterV3.write),
          offer.deliveryArea.map(StopArea.writerDomainV3.write),
          offer.walkToDestination.map(Walk.domainWriterV3.write),
          Some(TimeRange.writerV3.write(offer.deliveryTimeRange)),
          Some(NamedLocation.domainWriterV3.write(offer.destination)),
          Some(InstantWriter.write(offer.requestTime)),
          offer.timeOffset.map(to => DurationWriter.write(to.toDuration))
        )
    }

It would be nice if teleproto could do auto conversion even if the field names are different. Maybe we can declare an annotation to tell teleproto how to map a field if names are different.