fix: file saving when config path value is empty

[JManch]

This fixes a problem where setting path = "" would cause a "Fail making directory" error. I think it was due to the fs.path_exist function, but I've rewritten all of the file operation functions to use the seemingly more robust libuv library (it's also what most other plugins use).

I've also added functionality for detecting ltex files contain carriage returns and removing them if necessary. I ran into this problem on Windows where manually editing the ltex files added carriage returns, in turn breaking dictionary loading.

[barreiroleo]

Looks very good, I wanted to migrate this to libuv, thanks!