(vc-dired-update-line): Don't use dired-do-redisplay.

(vc-dired-update-line): Don't use dired-do-redisplay.
(vc-next-action-dired): Adjust default-directory before calling
vc-next-action-on-file.
(vc-next-action-on-file): Handle CVS merge in vc-dired-mode correctly.
(vc-next-action): Ask for a check-in comment if there are "added" CVS files.
Don't special-case single files in vc-dired-mode.
(vc-file-clear-masterprops): Typo fix.
(vc-latest-on-branch-p): Always true for CVS.
(vc-directory): Header change.  Do display the buffer, even if no
locked/registered files were found.