读写文件扩展名类型支持Unicode和多

代码说明：

一个文件读写的扩展类，支持unicode 和 多字符两字符集的文件的读写，还有重要的一点是读写中文的防止出现乱码。-Read and write a file extension type to support both unicode and multi-character character set of documents to read and write, there are important point is to prevent reading and writing Chinese characters.