ftptree 实现FTP连接，文件查看等

FTPTREE is a simple dialog application that has one edit box (for the name of the server and optionally a path to an object on that server) and a standard tree control object. The tree control belongs to the dialog box, and displays either an error message or the contents (up to 128 items) of an FTP site specified in the ftp:// edit box. The CInternetSession object encapsulates the connection to the Internet (or intranet). This object persists while the FTPTREE dialog exists in memory, though it could just as easily be opened only when needed (and closed immediately after) with little overhead. If an Internet session object cannot be initialized based on the configuration specified in the registry entry HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings, an error is displayed and the application shuts down.