Non-const Operation::getItems().
Moved ErrorCode to Operation.
Always add ErrorCode header in the generated packet.
Don't complain about EOFs.
Use noexcept instead of throw().
Added UnknownParentError.
Complain about unknown parent in enumerateItems().
Check seq only on update().
Added std::vector<std::string> to Fields_t variant.
+= is nicer for summing.
OpSummer::getOps().