粘贴代码时自动缩进

去除：:set paste
恢复：:set nopaste

显示行号

set number

reference

https://blog.csdn.net/wzy_1988/article/details/50264285
https://www.quanxiaoha.com/vim-command/vim-copy-all.html
https://zhangyiming748.github.io/post/vim_line_num