message: Great Merchant from first to discover Economics
diff: <iCost>1000</iCost>
  <iAdvancedStartCost>100</iAdvancedStartCost>
  <Era>ERA_RENAISSANCE</Era>
  - <FirstFreeUnitClass>UNITCLASS_GREAT_MERCHANT</FirstFreeUnitClass>
  <iAsset>40</iAsset>
  <bTrade>1</bTrade>
  <bGoodyTech>0</bGoodyTech>
  <iCost>1350</iCost>
  <iAdvancedStartCost>100</iAdvancedStartCost>
  <Era>ERA_RENAISSANCE</Era>
  + <FirstFreeUnitClass>UNITCLASS_GREAT_MERCHANT</FirstFreeUnitClass>
  <iAsset>44</iAsset>
  <bTrade>1</bTrade>
  <bGoodyTech>0</bGoodyTech>
  