build fix for mac os:
1) type_info visibility for CatapultAttack
2) using IObjectInfo::CArmyStructure in min_element : operator< should be const
another build fix:
Undefined symbols for architecture x86_64:
  "operator<<(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, EVictoryLossCheckResult const&)
Merge pull request #20 from Haryaalcar/develop

build fixes for mac os