bug#15631: 24.3; ido : invert effect of ido-restrict-to-matches with prefix arg

[Nicolas Richard <theonewiththeevillook@yahoo.fr>]

Hello

The function `ido-restrict-to-matches' is used within ido to restrict
focus on currently matched items. It was asked on #emacs to have a
function with the opposite effect : restrict focus on unmatched items.

I found it was useful for me and came up with this solution (adding an
optional argument to the existing function) :

diff --git a/lisp/ido.el b/lisp/ido.el
index cda4021..31aa303 100644
*** a/lisp/ido.el
--- b/lisp/ido.el
***************
*** 3133,3143 ****
        (if (> i 0)
  	  (setq ido-cur-list (ido-chop ido-cur-list (nth i ido-matches)))))))
  
! (defun ido-restrict-to-matches ()
!   "Set current item list to the currently matched items."
!   (interactive)
    (when ido-matches
!     (setq ido-cur-list ido-matches
  	  ido-text-init ""
  	  ido-rescan nil
  	  ido-exit 'keep)
--- 3133,3155 ----
        (if (> i 0)
  	  (setq ido-cur-list (ido-chop ido-cur-list (nth i ido-matches)))))))
  
! (defun ido-restrict-to-matches (&optional removep)
!   "Set current item list to the currently matched items.
! 
! When argument REMOVEP is non-nil, the currently matched items are
! instead removed from the current item list."
!   (interactive "P")
    (when ido-matches
!     (setq ido-cur-list (cond
!                         (removep
!                          (delq nil
!                                (mapcar
!                                 (lambda (elt)
!                                   (when (not (member elt ido-matches))
!                                     elt))
!                                 ido-cur-list)))
!                         (t ido-matches))
!           ido-matches ido-cur-list
  	  ido-text-init ""
  	  ido-rescan nil
  	  ido-exit 'keep)

-- 
Nicolas.