Dont open directory mode

Introduce

When enable "Don't open directory" mode, ivy-mode will only open file and don't open directory. if user want to open dirctory, another key should typed, for example: "C-f". This mode is simple and predictable.

When the below code is an example:

1. when type "enter", if current candidate is a directory, its subdir will be completed, if a file, open it.
2. if user want to open directory, type "C-f".

(require 'swiper)
(ivy-mode 1)

(setq ivy-extra-directories nil)

(defun eh-ivy-open-current-typed-path ()
  (interactive)
  (when ivy--directory
    (let* ((dir ivy--directory)
           (text-typed ivy-text)
           (path (concat dir text-typed)))
      (delete-minibuffer-contents)
      (ivy--done path))))

(define-key ivy-minibuffer-map (kbd "<return>") 'ivy-alt-done)
(define-key ivy-minibuffer-map (kbd "C-f") 'eh-ivy-open-current-typed-path)