message: Use reference syntax for factory
diff: @@ -437,11 +437,11 @@ void MapViewState::readStructures(Xml::XmlElement* element)
  if (structure.isFactory())
  {
  - Factory* factory = static_cast<Factory*>(&structure);
  - factory->productType(static_cast<ProductType>(production_type));
  - factory->productionTurnsCompleted(production_completed);
  - factory->resourcePool(&mPlayerResources);
  - factory->productionComplete().connect(this, &MapViewState::factoryProductionComplete);
  + auto& factory = *static_cast<Factory*>(&structure);
  + factory.productType(static_cast<ProductType>(production_type));
  + factory.productionTurnsCompleted(production_completed);
  + factory.resourcePool(&mPlayerResources);
  + factory.productionComplete().connect(this, &MapViewState::factoryProductionComplete);
  }
  /**
  