Move dired-guess commands from dired-x to dired

* lisp/dired-x.el (dired-shell-command-history)
(dired-guess-shell-alist-default, dired-guess-default)
(dired-guess-shell-command): Move from here...
* lisp/dired-aux.el (dired-shell-command-history)
(dired-guess-shell-alist-default, dired-guess-default)
(dired-guess-shell-command): ...to here.  (Bug#21981)

* lisp/dired-x.el (dired-guess-shell-gnutar)
(dired-guess-shell-gzip-quiet, dired-guess-shell-znew-switches)
(dired-guess-shell-case-fold-search, dired-guess-shell-alist-user):
Move from here...
* lisp/dired.el (dired-guess-shell-gnutar)
(dired-guess-shell-gzip-quiet, dired-guess-shell-znew-switches)
(dired-guess-shell-case-fold-search, dired-guess-shell-alist-user):
...to here.  Change :group to dired-guess.
(dired-guess): New defgroup.

* test/lisp/dired-x-tests.el (dired-guess-default): Move from here...
* test/lisp/dired-aux-tests.el (dired-guess-default): ...to here.

* doc/misc/dired-x.texi (Features, Technical Details, Installation):
Delete any mention of shell command guessing.
(Shell Command Guessing): Move from here...
* doc/emacs/dired.texi (Shell Command Guessing): ...to here.  Adapt to
better fit the Emacs Manual conventions.
* lisp/dired-aux.el (dired-do-shell-command): Doc fix to adjust for
above changes.
* etc/NEWS: Announce the above change.

2 files changed, 13 insertions, 13 deletions

diff --git a/test/lisp/dired-aux-tests.el b/test/lisp/dired-aux-tests.el
index 694deaae4c2..e70898ab74e 100644
--- a/test/lisp/dired-aux-tests.el
+++ b/test/lisp/dired-aux-tests.el
@@ -154,5 +154,18 @@
     (should (string-match (regexp-quote command) (nth 0 lines)))
     (dired-test--check-highlighting (nth 0 lines) '(8))))
 
+(ert-deftest dired-guess-default ()
+  (let ((dired-guess-shell-alist-user nil)
+        (dired-guess-shell-alist-default
+         '(("\\.png\\'" "display")
+           ("\\.gif\\'" "display" "xloadimage")
+           ("\\.gif\\'" "feh")
+           ("\\.jpe?g\\'" "xloadimage"))))
+    (should (equal (dired-guess-default '("/tmp/foo.png")) "display"))
+    (should (equal (dired-guess-default '("/tmp/foo.gif"))
+                   '("display" "xloadimage" "feh")))
+    (should (equal (dired-guess-default '("/tmp/foo.png" "/tmp/foo.txt"))
+                   nil))))
+
 (provide 'dired-aux-tests)
 ;;; dired-aux-tests.el ends here
diff --git a/test/lisp/dired-x-tests.el b/test/lisp/dired-x-tests.el
index cec266b0ef9..7acaa3c1319 100644
--- a/test/lisp/dired-x-tests.el
+++ b/test/lisp/dired-x-tests.el
@@ -47,19 +47,6 @@
       (should (equal all-but-c
                      (sort (dired-get-marked-files 'local) #'string<))))))
 
-(ert-deftest dired-guess-default ()
-  (let ((dired-guess-shell-alist-user nil)
-        (dired-guess-shell-alist-default
-         '(("\\.png\\'" "display")
-           ("\\.gif\\'" "display" "xloadimage")
-           ("\\.gif\\'" "feh")
-           ("\\.jpe?g\\'" "xloadimage"))))
-    (should (equal (dired-guess-default '("/tmp/foo.png")) "display"))
-    (should (equal (dired-guess-default '("/tmp/foo.gif"))
-                   '("display" "xloadimage" "feh")))
-    (should (equal (dired-guess-default '("/tmp/foo.png" "/tmp/foo.txt"))
-                   nil))))
-
 (ert-deftest dired-x--string-to-number ()
   (should (= (dired-x--string-to-number "2.4K") 2457.6))
   (should (= (dired-x--string-to-number "2400") 2400))