Inspired by https://blog.debiania.in.ua/posts/2012-07-31-purging-vim-undodir.html
Implement it with pure vimscript for multiple platform support.
vim persistent-undo feature is very useful, but it will always keep the undofile in undodir,
even the original file was already deleted.
This plugin will purge these undofile for you. 😄
Tested in vim/neovim on Windows/Linux/macOS
This plugin will running on VimLeave.
You can also run it manually by :call purge_undodir#purge()