remove window-numbering-before-hook

its sole obvious utility was redundant with `winum-assign-func` while
being more complicated to use.

Let me know if you miss that functionality.

README.org

@@ -102,15 +102,6 @@ If non-nil, =winum-mode= assigns 0 to the minibuffer if active.
 
 Default: t
 
-- =winum-before-hook=
-
-Hook called before =winum-mode= starts assigning numbers. The list of
-windows to be numbered is passed as a parameter. Use =winum--assign=
-to manually assign some of them a number. If you want to assign a number to just
-one buffer, use =winum-assign-func= instead.
-
-Default: nil
-
 - =winum-assign-func=
 
 Function called for each window by =winum-mode=. This is called

winum.el

@@ -72,16 +72,6 @@ Has effect only when `winum-scope' is not 'frame-local."
   :group 'winum
   :type  'boolean)
 
-;; TODO see if useful
-(defcustom winum-before-hook nil
-  "Hook called before `winum-mode' starts assigning numbers.
-The list of windows to be numbered is passed as a parameter.
-Use `winum--assign' to manually assign some of them a number.
-If you want to assign a number to just one buffer, use
-`winum-assign-func' instead."
-  :group 'winum
-  :type  'hook)
-
 (defcustom winum-assign-func nil
   "Function called for each window by `winum-mode'.
 This is called before automatic assignment begins.  The function should
@@ -296,7 +286,6 @@ POSITION: position in the mode-line."
              (active-minibuffer-window))
     (winum--assign (active-minibuffer-window) 0))
   (let ((windows (winum--window-list)))
-    (run-hook-with-args 'winum-before-hook windows)
     (when winum-assign-func
       (mapc (lambda (w)
               (with-selected-window w