bug#14925: 24.3.50; `image-dired.el' code (minor)

[Drew Adams <drew.adams@oracle.com>]

Generally, it would be better if `image-dired.el' followed the
conventions used in dired.el, dired-aux.el, and dired-x.el wrt (a)
naming and (b) parameter ARG (prefix argument).  That helps users by
providing relatively consistent command names and UI behavior.

Also a minor coding remark (#1).

1. `image-dired-dired-file-marked-p' uses regexp "^ .*$", which I think
is the same as "^ " (which is simpler).  I also wonder why it does not
just use `dired-re-mark'.

2. Commands that act on the marked files should perhaps follow the
naming convention used in dired.el, dired-aux.el, and dired-x.el:
`*-do-*'.  Thus perhaps rename `image-dired-dired-comment-files',
`image-dired-tag-files', `image-dired-delete-tag',
`image-dired-display-thumbs', `image-dired-copy-with-exif-file-name',
`image-dired-dired-edit-comment-and-tags', and
`image-dired-create-thumbs'.

The equivalent Dired command that acts on the current file only, when
available, is named similarly, but without the `*-do-*' part.

3. Those commands do not treat parameter ARG the same way as do the
Dired `*-do-*' commands.  For the image-dired commands, ARG is
essentially boolean (and should thus have a name that reflects that).
Wouldn't it be better for it to be the `prefix-numeric-value' and let
you act on the next ARG files?  That would give users more flexibility
and provide a more consistent UI.  Is there a downside I am missing?


In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-07-14 on ODIEONE
Bzr revision: 113423 lekktu@gmail.com-20130715004922-i67tg2ois14h3fpm
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 CFLAGS='-O0 -g3' CPPFLAGS='-Ic:/Devel/emacs/include'
 LDFLAGS='-Lc:/Devel/emacs/lib''