message: Use attributesToDictionary to read maintenance facility assignment
  Set a default value of 0 if no attribute was found. Previously this
  value was left unset in that case.
diff: @@ -463,12 +463,7 @@ void MapViewState::readStructures(Xml::XmlElement* element)
  if (personnel)
  {
  auto maintenanceFacility = static_cast<MaintenanceFacility*>(&structure);
  - auto assigned = personnel->attribute("assigned");
  - if (!assigned.empty())
  - {
  - maintenanceFacility->personnel(std::stoi(assigned));
  - }
  -
  + maintenanceFacility->personnel(attributesToDictionary(*personnel).get<int>("assigned", 0));
  maintenanceFacility->resources(mResourcesCount);
  }
  }
  