[VM] Prefix Argument for Viewing Links

[Josh Braun]

In order to follow an insecure or "unsafe" link in VM, the user must
currently use the prefix argument before launching the URL. I.e., she
must type C-u ENTER while the cursor is overtop the link.

This behavior is fine, but I saw the following thread on the GNU
Emacs-Devel list recently in which the developers are considering
using the same key combination differently with regard to links:

http://lists.gnu.org/archive/html/emacs-devel/2013-12/msg00438.html

If adopted, it looks as though this proposed feature--which I actually
rather like--may create a conflict, or at least a contextual difference
in how links are treated, between VM and other Emacs modes. I thought it
might be good to make a note of this possibility while it's still on the
horizon, rather than after it's implemented.

Cheers,
Josh

P.S. I'm not the same "Josh" commenting on the Emacs-Devel thread, lest
there be any confusion.