"help" key with Cocoa Emacs 23

[Jonathan Groll]

It seems that the "help" key on an external Apple keyboard is not
detected by Emacs 23 Cocoa.

C-h k does not detect this key (the "delete" key is detected this
way).

Previously Aquamacs was able to detect this key, and in Aquamacs this
key could be rebound with something like:

(global-set-key [help] 'overwrite-mode)

GNU Emacs 23.0.60.1 (i386-apple-darwin9, NS apple-appkit-949.35)
of 2008-11-20 on a white macbook.

Cheers,
Jonathan