bug#29215: 26.0; `dired-isearch-filter-filesnames`: be able to match prefix

[Eli Zaretskii]

> Date: Wed, 8 Nov 2017 08:13:17 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> 
> 1. Typo in first line of doc string:
> 
>    Test whether the current search hit is a file name.
> 
>    It does not test whether the search hit is a file name.
>    It tests whether the search hit is IN a file name.
> 
> 2. Please provide a fix or enhancement that lets users match a search
>    pattern at the beginning of a file name.  With
>    `dired-isearch-filenames-regexp', for example, using "`\f" or "^f"
>    does not match a file name that begins with "f".  It's not obvious
>    how to match the beginning of a file name.

Thanks, I fixed the first item on the release branch.

(Lumping more than one issue in the same report is baaad, mmkay?)