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

[Drew Adams]

> > 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)
> 
> Such compromise keys do not do any good neither to ido users
> nor to non-ido users.

Agreed.  But Ido users presumably do not need Icomplete anyway.  It is non-Ido
users that we should be concerned about for Icomplete.

> Better would be to add an option like `icomplete-enable-ido-keys' that
> when set to t will define ido-specific bindings on `C-s' and `C-r'.

Yes, but without "ido" in the name.  It is about enabling keys (any keys) for
Icomplete.  It is not about enabling Ido keys for Icomplete.

The keys to use by default can be whatever you like, but they should be specific
to Icomplete (i.e., in its own, independent keymap, as now).

I.e., even if the keys used by default are identical to those used in Ido by
default, there should be no other connection.  Since users will be free to
change them in either place separately, the option name should be unrelated to
Ido.