Add helpers for auto enabling inf-clojure

[arichiardi]

Hi all,
I was wondering if these kind of helpers could be useful to include in inf-clojure:

(defcustom inf-clojure-auto-enable-extensions
  '("joke" "lumo")
  "List of extensions to use for auto enable of `inf-clojure-minor-mode."
  :type 'list
  :group 'clojure)

(defun inf-clojure--enable-for-known-extensions ()
  "Enable inf-clojure-minor-mode for some known extensions."
  (when (and (not (bound-and-true-p inf-clojure-minor-mode))
             (member (file-name-extension buffer-file-name) inf-clojure-auto-enable-extensions))
    (inf-clojure-minor-mode)))

(defun inf-clojure--disable-cider-for-known-extensions ()
  "Disable cider-mode for known extensions."
  (when (and (bound-and-true-p cider-mode)
             (member (file-name-extension buffer-file-name) inf-clojure-auto-enable-extensions))
    (cider-mode -1)))

They are kind of useful for me to switch between cider-mode adn inf-clojure-minor-mode depending on the extension.