Prefix map

Generate a hydra from a prefix map

See #335. Relies on which-key.

(require 'evil)
(require 'which-key)
(eval
 `(defhydra hydra-evil-window-map (:columns 2)
    ,@(mapcar (lambda (x)
                (list (car x) (intern (cdr x)) (cdr x)))
              (which-key--get-keymap-bindings evil-window-map t))
    ("q" nil "quit")))
(hydra-evil-window-map/body)