bug#37514: PATCH: Add setting to allow switching to an already-visible buffer by default

[Juri Linkov]

>> C-x <C-left>, C-x <left>, <XF86Back>
>> C-x <C-right>, C-x <right>, <XF86Forward>
>
> These are not auto-repeatable, alas.

At least we need to add a numeric arg to make them more repeatable
with e.g. 'C-3 C-x <C-left>' - easy to type key sequence
while holding the Ctrl key.

> To me that's two bugs in the completions mechanism itself.  It does
> propose *Messages* first although that buffer is already displayed in
> another window and does not propose *scratch* although that buffer
> does not show in another window.  For me, a correct interpretation of
> C-x 4 b is to propose *scratch* first and _maybe_ propose *Messages*
> additionally for people who don't like C-x o.  C-x b in the very same
> configuration does it right IMHO.

Since here different preferences make sense, maybe this needs
better customizability.