* lisp/vc/vc-dir.el (vc-dir-mark-file): Prompt before unmarking all subitems. Use y-or-n-p and user-error instead of yes-or-no-p and error. (vc-dir-unmark-file): Use y-or-n-p instead of yes-or-no-p. (vc-dir-allow-mass-mark-changes): Update docs.