Method extension

src/attributes.cpp:75–81

        double lastModified() const { return lastModified_; }

        std::string extension() const {
            std::string::size_type pos = path_.find_last_of('.');
            if (pos != std::string::npos)
                return path_.substr(pos);
            else
                return "";					// #nocov
        }

        bool operator<(const FileInfo& other) const {
            return path_ < other.path_;