Clean up remote tracking

[zenspider]

This is on top of mamewotoko's feature/without_user_name

[zenspider]

Poke. I'd really like to see this go upstream... this is the only way I've gotten remote editing to work properly.

For those having problems and coming upon this PR. I use this in my ssh-mode-hook in order to get everything working:

;; (ssh-directory-tracking-mode) -- causes an error on connection
(shell-dirtrack-mode t)
(setq ssh-directory-tracking-mode t)
(setq shell-dirtrackp t)
(setq comint-file-name-prefix (make-comint-file-name-prefix))