Any reason why $HOME can't be used as the first choice in get_home_directory?

I'm on Cygwin, and `get_home_directory` returns my Windows path (`C:\Users\readparse`) instead of my actual home directory (`/home/readparse`), which is correct in `$HOME`.  I would have expected `$HOME` to be the default, actually.  Perhaps there's a reason why it's not.   

Anyway, if you're open to it, I propose this simple patch.  Thanks for this project.  It's a great tool.