message: Add mean crime rate to save file
  Otherwise value will not be correct when loading a game until the next turn.
diff: @@ -113,6 +113,7 @@ void MapViewState::save(const std::string& filePath)
  population->attribute("workers", mPopulation.size(Population::PersonRole::ROLE_WORKER));
  population->attribute("scientists", mPopulation.size(Population::PersonRole::ROLE_SCIENTIST));
  population->attribute("retired", mPopulation.size(Population::PersonRole::ROLE_RETIRED));
  + population->attribute("mean_crime", mPopulationPanel.crimeRate());
  root->linkEndChild(population);
  auto moraleChangeReasons = new XmlElement("morale_change");
  @@ -536,6 +537,12 @@ void MapViewState::readPopulation(Xml::XmlElement* element)
  attribute->queryIntValue(mPreviousMorale);
  mPopulationPanel.old_morale(mPreviousMorale);
  }
  + else if (attribute->name() == "mean_crime")
  + {
  + int meanCrimeRate = 0;
  + attribute->queryIntValue(meanCrimeRate);
  + mPopulationPanel.crimeRate(meanCrimeRate);
  + }
  else if (attribute->name() == "colonist_landers") { attribute->queryIntValue(mLandersColonist); }
  else if (attribute->name() == "cargo_landers") { attribute->queryIntValue(mLandersCargo); }
  