bug#14013: 24.3.50; dired-isearch-filenames-regexp is matching text outside filenames

[Juri Linkov]

>> So the above rectangle when copied to a separate buffer:
>>
>>       456
>>       def
>>
>> do you expect it should match the regexp "456.def"?
>
> I would not want that this matches.

I generalized dired-isearch-search-filenames to a new function
that can search in any text property, so e.g. after evaluating

  (setq-local isearch-search-fun-function
  (lambda () (isearch-search-fun-in-text-property 'face)))

isearch will match .* in all fontified chunks, etc.