rem: void extract_files(const entry::list_type& list, std::vector<file_entry>& target)
add: void extract_files(const entry::list_type& list, std::vector<file_entry>& target , std::string const& root_dir)
context: 	void extract_files(const entry::list_type& list, std::vector<file_entry>& target)	{		for (entry::list_type::const_iterator i = list.begin(); i != list.end(); ++i)		{			target.push_back(file_entry());			extract_single_file(*i, target.back());		}	}