Make vc-toggle-read-only an alias for toggle-read-only.

Make vc-toggle-read-only an alias for toggle-read-only.

It hasn't worked in a VC sense since 2008-05-02T07:12:59Z!esr@snark.thyrsus.com, though this was
not documented at the time (grr).

* lisp/vc/vc-hooks.el (vc-toggle-read-only): Make it an obsolete alias
for toggle-read-only.  Note that this hasn't called vc-next-action
since 2008-05-02, though it wasn't documented at the time.

* lisp/files.el (toggle-read-only): Remove obsolete comment about
version control.

* doc/emacs/buffers.texi (Misc Buffer): Don't mention vc-toggle-read-only.

* lisp/cedet/ede.el (ede-maybe-checkout): Function deleted;
vc-toggle-read-only does not do version control now.

* lisp/cedet/ede/project-am.el (project-remove-file, project-add-file)
(project-new-target): Don't call ede-maybe-checkout.

* lisp/cedet/ede/util.el (ede-make-buffer-writable): Don't use
vc-toggle-read-only.

* lisp/vc/ediff-init.el (ediff-toggle-read-only-function): Use
toggle-read-only.