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

[Juri Linkov]

>> So that design decision and the resulting code we have now had some
>> justification, and any replacement will have to support the same
>> features, which I think a simple string will not do.
>
> Ok, thanks for explanation, perhaps you can close this bug.

Thanks, Thierry, I installed your second patch (from 20 Jan)
with some modifications.

As for your idea of using plain ASCII separators without text properties,
the problem is that it will not work if the user wants to replace
the same string as is used for the separator, e.g. to replace
→ with  -> in the current buffer.  If you have more ideas how
to make the separator unambiguous without using text properties,
then please reopen this bug.