extern void check_xml (boost::filesystem::path, boost::filesystem::path, std::list<std::string>);
extern void check_file (boost::filesystem::path, boost::filesystem::path);
extern void check_image (boost::filesystem::path, boost::filesystem::path);
extern void check_xml (boost::filesystem::path, boost::filesystem::path, std::list<std::string>);
extern void check_file (boost::filesystem::path, boost::filesystem::path);
extern void check_image (boost::filesystem::path, boost::filesystem::path);