message: Vassalage: remove happiness from Castle
diff: <iBaseFreeUnits>15</iBaseFreeUnits>
  <iFreeUnitsPopulationPercent>10</iFreeUnitsPopulationPercent>
  <iLargestCityHappiness>2</iLargestCityHappiness>
  - <BuildingHappinessChanges>
  - <BuildingHappinessChange>
  - <BuildingType>BUILDINGCLASS_CASTLE</BuildingType>
  - <iHappinessChange>1</iHappinessChange>
  - </BuildingHappinessChange>
  - </BuildingHappinessChanges>
  <ImprovementYieldChanges>
  <ImprovementYieldChange>
  <ImprovementType>IMPROVEMENT_FARM</ImprovementType>
  