Support XDG directories on Windows

[julie777]

By support I don't mean put in all the Linux defaults, but rather if XDG environment variables are set then use them. If not use the Windows defined directories.

This won't affect anyone who has not set XDG variables in their environment.

This provides maximum flexibility and allows for consistency for developers.

I share my HOME directory tree and dot files between Windows and WSL Ubuntu. For any program that provides a way to configure directories I use the typical XDG directories with platform qualifiers as necessary. This provides a very consistent and convenient development environment.

[gaborbernat]

Thanks for opening the issue, however as the #4 details the maintainers of this project decided against this. Therefore, we'll not be adding this functionality.