bug#29321: Isearch hit count

[Juri Linkov]

> But please note that it contains a new implementation
> because I found problems in the previous implementation:
> when COUNT is added to low-level isearch functions then
> they don't skip filtered-out matches.
>
> So a better place is in isearch-search after
> `funcall isearch-filter-predicate'.  But the problem
> is that when (= (match-beginning 0) (match-end 0))
> then it doesn't move point one character forward like
> isearch-repeat does.  So the right place to use COUNT is in
> isearch-repeat.
>
> Please try a new implementation:

Now this is pushed to master.