Revert my change to gnus-art.el

* lisp/gnus/gnus-art.el (gnus-button-alist): Revert last change.
It wasn't that important, and it caused a Gnus build to fail.  See:
http://www.randomsample.de:4456/builders/emacs-devel/builds/734

lisp/gnus/gnus-art.el

@@ -7827,11 +7827,11 @@ positives are possible."
     ("/\\([a-z][-a-z0-9]+\\.el\\)\\>[^.?]"
      ;; Exclude [.?] for URLs in gmane.emacs.cvs
      1 (>= gnus-button-emacs-level 8) gnus-button-handle-library 1)
-    ("[`‘]\\([a-z][-a-z0-9]+\\.el\\)['’]"
+    ("`\\([a-z][-a-z0-9]+\\.el\\)'"
      1 (>= gnus-button-emacs-level 8) gnus-button-handle-library 1)
-    ("[`‘]\\([a-z][a-z0-9]+-[a-z0-9]+-[-a-z0-9]*[a-z]\\|\\(gnus\\|message\\)-[-a-z]+\\)['’]"
+    ("`\\([a-z][a-z0-9]+-[a-z0-9]+-[-a-z0-9]*[a-z]\\|\\(gnus\\|message\\)-[-a-z]+\\)'"
      0 (>= gnus-button-emacs-level 8) gnus-button-handle-symbol 1)
-    ("[`‘]\\([a-z][a-z0-9]+-[a-z]+\\)['’]"
+    ("`\\([a-z][a-z0-9]+-[a-z]+\\)'"
      0 (>= gnus-button-emacs-level 9) gnus-button-handle-symbol 1)
     ("(setq[ \t\n]+\\([a-z][a-z0-9]+-[-a-z0-9]+\\)[ \t\n]+.+)"
      1 (>= gnus-button-emacs-level 7) gnus-button-handle-describe-variable 1)
@@ -7841,7 +7841,7 @@ positives are possible."
      0 (>= gnus-button-emacs-level 1) gnus-button-handle-describe-function 2)
     ("\\b\\(C-h\\|<?[Ff]1>?\\)[ \t\n]+v[ \t\n]+\\([^ \t\n]+\\)[ \t\n]+RET\\>"
      0 (>= gnus-button-emacs-level 1) gnus-button-handle-describe-variable 2)
-    ("[`‘]\\(\\(C-h\\|<?[Ff]1>?\\)[ \t\n]+k[ \t\n]+\\([^'’]+\\)\\)['’]"
+    ("`\\(\\(C-h\\|<?[Ff]1>?\\)[ \t\n]+k[ \t\n]+\\([^']+\\)\\)'"
      ;; Unlike the other regexps we really have to require quoting
      ;; here to determine where it ends.
      1 (>= gnus-button-emacs-level 1) gnus-button-handle-describe-key 3)