bug#23179: 25.0.92; Restore `M-,' to continue etags search

[Juri Linkov <juri@linkov.net>]

>>>>     M-x project-search
>>>>
>>>>       1. can't use M-n to get the default value such as a word under point
>>>>          like project-find-regexp does
>
> But the answer would be the same: it's not hard to implement for whoever is
> interested. The easiest fix would be to simply use project--read-regexp in
> the interactive spec, but it shows a different prompt, which might or might
> not be a problem (the prompts follow their commands' names).

If project-search searches for a regexp, then using a read-regexp
is the right thing.

>>>>     M-x fileloop-continue
>>>>
>>>>       2. its name prefix is inconsistent with the prefix of its
>>>>          counterpart command project-search
>>>
>>> It doesn't have to. fileloop-continue is intended to be used with different
>>> commands (e.g. some with dired- prefix as well).
>>
>> Maybe an alias with another prefix is in order?
>
> I don't think so. Or else the next step would be to set up multiple
> different key bindings, one for each alias. Which is obviously silly.

Then all these commands could share the same key prefix.

>>>>       3. no keybinding
>>>
>>> There's no keybinding for project-search either. The user is welcome to
>>> choose some.
>>
>> Maybe 'M-g M-n'?
>
> That's 'next-error', isn't it?
>
> Again, the user is welcome to choose whatever key binding that suits them.
>
> project-find-regexp, which is a lot handier IMO, has no default key binding
> either. I'm using 'C-x g'.

Maybe something like 'M-g f r' with a mnemonics "go find regexp".