[PD] one other OS X related minor issue

[Anthony Saunders]

this is another minor issue, but more directly related to getting work 
done.

I realize that PD isn't a fully aqua app at this point, but is it 
possible to somehow enable window-switching via the cmd-` shortcut that 
is used in most other apps? or any kind of "next window" option with a 
shortcut.

makes it easier to deal with lots of patchers.

currently just using expose instead.

Anthony