bug#4677: allow VC operations from dired

[Dan Nicolaescu <dann@ics.uci.edu>]

This patch allows VC operations to be run from dired.
State changing VC operations are not supported. 
(only the various variations of log and diff)

OK to check in?

Index: vc.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/vc.el,v
retrieving revision 1.732
diff -u -3 -p -r1.732 vc.el
--- vc.el	3 Oct 2009 18:29:26 -0000	1.732
+++ vc.el	8 Oct 2009 20:17:08 -0000
@@ -634,7 +634,8 @@
 (require 'vc-dispatcher)
 
 (eval-when-compile
-  (require 'cl))
+  (require 'cl)
+  (require 'dired))
 
 (unless (assoc 'vc-parent-buffer minor-mode-alist)
   (setq minor-mode-alist
@@ -889,6 +903,10 @@ current buffer."
     (cond
      ((derived-mode-p 'vc-dir-mode)
       (vc-dir-deduce-fileset state-model-only-files))
+     ((derived-mode-p 'dired-mode)
+      (if observer
+	  (vc-dired-deduce-fileset)
+	(error "State changing VC operations not supported in `dired-mode'")))
      ((setq backend (vc-backend buffer-file-name))
       (if state-model-only-files
 	(list backend (list buffer-file-name)
@@ -921,4 +939,9 @@
 
+
+(defun vc-dired-deduce-fileset ()
+  (list (vc-responsible-backend default-directory)
+	(dired-map-over-marks (dired-get-filename nil t) nil)))
+
 (defun vc-ensure-vc-buffer ()
   "Make sure that the current buffer visits a version-controlled file."
   (cond
@@ -1590,6 +1613,7 @@ saving the buffer."
     (when buffer-file-name (vc-buffer-sync not-urgent))
     (let ((backend
 	   (cond ((derived-mode-p 'vc-dir-mode)  vc-dir-backend)
+		 ((derived-mode-p 'dired-mode) (vc-responsible-backend default-directory))
 		 (vc-mode (vc-backend buffer-file-name))))
 	  rootdir working-revision)
       (unless backend
@@ -1881,6 +1905,7 @@ If WORKING-REVISION is non-nil, leave th
   (interactive)
   (let ((backend
 	 (cond ((derived-mode-p 'vc-dir-mode)  vc-dir-backend)
+	       ((derived-mode-p 'dired-mode) (vc-responsible-backend default-directory))
 	       (vc-mode (vc-backend buffer-file-name))))
 	rootdir working-revision)
     (unless backend