winform实现自动更新，对比本地文件和远程xml版本文件，对版本需要升级的，先下载下来，保存到临时盘，复制主程序文件后删除临时文件，升级完成-WinForm automatic updates, in contrast to local files and remote XML version of the document, the need to upgrade the first version, download, save to temporary disk copy, main