message: Correct Steamship upgrades
diff: <iWithdrawalProb>25</iWithdrawalProb>
  <UnitClassUpgrades>
  <UnitClassUpgrade>
  - <UnitClassUpgradeType>UNITCLASS_TRANSPORT</UnitClassUpgradeType>
  + <UnitClassUpgradeType>UNITCLASS_STEAMSHIP</UnitClassUpgradeType>
  <bUnitClassUpgrade>1</bUnitClassUpgrade>
  </UnitClassUpgrade>
  </UnitClassUpgrades>
  <bMechanized>1</bMechanized>
  <bRenderBelowWater>1</bRenderBelowWater>
  <iWithdrawalProb>25</iWithdrawalProb>
  + <UnitClassUpgrades>
  + <UnitClassUpgrade>
  + <UnitClassUpgradeType>UNITCLASS_TRANSPORT</UnitClassUpgradeType>
  + <bUnitClassUpgrade>1</bUnitClassUpgrade>
  + </UnitClassUpgrade>
  + </UnitClassUpgrades>
  <UnitAIs>
  <UnitAI>
  <UnitAIType>UNITAI_ASSAULT_SEA</UnitAIType>
  