bug#13602: 24.3.50; remove bindings for `icomplete-minibuffer-map' - make a separate mode

[Stefan Monnier]

> How about C-S-s and C-S-r?  I just need to have Shift key depressed,
> which is fine with me.

>     (define-key map [?\C-\S-s]  'icomplete-forward-completions)
>     (define-key map [?\C-\S-r]  'icomplete-backward-completions)

I'm not very much in favor:
- in my environment, C-S-r works but C-S-s is not received by Emacs
  (maybe XFCE catches it?).
- it won't work in ttys.
- I find it cumbersome to type.
None of them are deal breakers.


        Stefan