* Add a proto RoutingSearchStatus::Value
* Add RoutingModel::status()
* replace std::vector by absl::Span
* Rework energy cost (add a threshold)
* Add a PARALLEL_SAVING First Solution Strategy
* Extract BoundCost from SimpleBoundCost since SWIG do not support
nested class
* Wrap it in all languages
* Expose new API
* SoftSpanUpperBoundForVehicle
* QuadraticCostSoftSpanUpperBoundForVehicle
* Add tests