bug#3963: 23.0.94; Emacs on nextstep/Mac OS X should handle mailto: URLs

[Harald Hanche-Olsen <hanche@math.ntnu.no>]

In Mail.app on Mac OS X, open Preferences -> General, and select Emacs
as the the default email reader.
Quit Mail.app and never use it again. 8-)

Now click on a mailto: link in your favourite web browser, or else run
a command like this:  open mailto:nobody@example.com

Notice that Emacs comes to the foreground, but nothing more happens.
What SHOULD happen is that Emacs opens a new draft email message
addressed to the named recipient.

Note that the nextstep port is already capable of similar feats, using
the Service menu in any application; but this is more important, as
users click on mailto links all the time, and we don't want to
discourage their use of Emacs for email.


In GNU Emacs 23.0.94.1 (i386-apple-darwin9.7.1, NS apple-appkit-949.46)
 of 2009-06-17 on mach.local
Windowing system distributor `Apple', version 10.3.949
configured using `configure  '--with-ns''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t