bug#25482: 26.0.50; Allow setting `query-replace-from-to-separator` to nil

[Eli Zaretskii]

> Date: Mon, 13 Feb 2017 16:24:41 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 25482@debbugs.gnu.org, thierry.volpiatto@gmail.com
> 
> > > Thanks, but please also update NEWS and the Emacs manual with the
> > > information about the new nil value of the separator.
> > 
> > I updated NEWS, but not the Emacs manual because the new nil value
> > is useful only for some old users (who want its old behavior),
> > not for new users.
> 
> Why would you suppose that?  The behavior, which includes nil as
> a possible value, should be described.  Let users decide whether
> this or that value is better for them.  Please document the option
> correctly.

Done.