message: extended_symbol compare
diff: @@ -215,6 +215,10 @@ namespace eosio {
  return std::tie( a.value, a.contract ) != std::tie( b.value, b.contract );
  }
  + friend bool operator < ( const extended_symbol& a, const extended_symbol& b ) {
  + return std::tie( a.value, a.contract ) < std::tie( b.value, b.contract );
  + }
  +
  EOSLIB_SERIALIZE( extended_symbol, (value)(contract) )
  };
  