core-lib: add auto-minor-mode, revise def-project-mode!

- Adds the auto-minor-mode package to replace our in-house
  implementation.
- Merges associate! into the def-project-mode! macro because associate!
  on its own is less useful than auto-minor-mode-alist,
  auto-minor-mode-magic-alist or hooks.
- Changes the semantics of :modes and :add-hooks properties of
  def-project-mode!. Its arguments are evaluated as is; lists will need
  to be quoted.

squash! core-lib: remove associate! macro

modules/lang/python/config.el

@@ -109,7 +109,7 @@ called.")
 (def-package! nose
   :commands nose-mode
   :preface (defvar nose-mode-map (make-sparse-keymap))
-  :init (associate! nose-mode :match "/test_.+\\.py$" :modes (python-mode))
+  :minor-mode ("/test_.+\\.py$" . nose-mode)
   :config
   (set-popup-rule! "^\\*nosetests" :size 0.4 :select nil)
   (set-yas-minor-mode! 'nose-mode)