message: Some promotions require techs
  Generalship -> Formation
  Seafaring -> Amphibious
  Medicine -> Medic I
  Logistics -> Medic III
diff: <Sound>AS2D_IF_LEVELUP</Sound>
  <PromotionPrereqOr1>PROMOTION_COMBAT2</PromotionPrereqOr1>
  <PromotionPrereqOr2>PROMOTION_DRILL2</PromotionPrereqOr2>
  + <TechPrereq>TECH_GENERALSHIP</TechPrereq>
  <UnitCombatMods>
  <UnitCombatMod>
  <UnitCombatType>UNITCOMBAT_MOUNTED</UnitCombatType>
  <Description>TXT_KEY_PROMOTION_AMPHIBIOUS</Description>
  <Sound>AS2D_IF_LEVELUP</Sound>
  <PromotionPrereqOr1>PROMOTION_COMBAT2</PromotionPrereqOr1>
  + <TechPrereq>TECH_SEAFARING</TechPrereq>
  <bAmphib>1</bAmphib>
  <bRiver>1</bRiver>
  <UnitCombats>
  <Sound>AS2D_IF_LEVELUP</Sound>
  <PromotionPrereqOr1>PROMOTION_COMBAT1</PromotionPrereqOr1>
  <PromotionPrereqOr2>PROMOTION_DRILL1</PromotionPrereqOr2>
  + <TechPrereq>TECH_MEDICINE</TechPrereq>
  <iSameTileHealChange>10</iSameTileHealChange>
  <UnitCombats>
  <UnitCombat>
  <Sound>AS2D_IF_LEVELUP</Sound>
  <PromotionPrereq>PROMOTION_LEADER</PromotionPrereq>
  <PromotionPrereqOr1>PROMOTION_MEDIC2</PromotionPrereqOr1>
  + <TechPrereq>TECH_LOGISTICS</TechPrereq>
  <iSameTileHealChange>15</iSameTileHealChange>
  <iAdjacentTileHealChange>15</iAdjacentTileHealChange>
  <UnitCombats>
  