message: Reduce Constabulary cost to 150
diff: <ArtDefineTag>ART_DEF_BUILDING_CONSTABULARY</ArtDefineTag>
  <PrereqTech>TECH_JUDICIARY</PrereqTech>
  <iAIWeight>25</iAIWeight>
  - <iCost>180</iCost>
  + <iCost>150</iCost>
  <iAdvancedStartCost>100</iAdvancedStartCost>
  <iMinAreaSize>-1</iMinAreaSize>
  <iConquestProb>75</iConquestProb>
  <ArtDefineTag>ART_DEF_BUILDING_CANADIAN_ROYAL_MOUNTED_POLICE</ArtDefineTag>
  <PrereqTech>TECH_JUDICIARY</PrereqTech>
  <iAIWeight>25</iAIWeight>
  - <iCost>180</iCost>
  + <iCost>150</iCost>
  <iAdvancedStartCost>100</iAdvancedStartCost>
  <iMinAreaSize>-1</iMinAreaSize>
  <iConquestProb>75</iConquestProb>
  