Deprecate CR mode 弃用CR换行模式

[cup113]

As we know, CR mode have been deprecated by macOS. So we don't need to think about it and only use CRLF and LF while reading .txt files. It can also help improve the speed of reading.
CR换行模式已经被macOS弃用了。因此，在阅读txt文件时，我们只需要考虑CRLF和LF换行模式，这也可以帮助我们提高阅读的速度。