Mac OS Command Key as <ALT> Patch

[Andrew Choi]

Hi,

I have added a small change to src/macterm.c that will allow Emacs on
the Mac OS to recognize the Mac command key as <ALT> when the Mac
option key is used as <META>.  This is useful for people who want to
map cut, copy, and paste to the familiar command-X, command-C, and
command-V, for example.

This will not affect people using the Mac command key as <META>.

Andrew.