[SDL] Cocoa window menus in 1.3

[Sam Lantinga]

> Why was it needed in 1.2 but not 1.3 ?

SDLmain was the natural place to start the NSApplication, especially
since it normally takes the argc/argv parameters.  SDLmain also filtered
out Finder arguments, and translated file drop requests, none of which
is supported in the SDLmain-less 1.3.

However, I think I've set it up so that you can still use a nib, and your
own SDLmain with SDL 1.3, if you want to, it's just no longer required.

See ya,
	-Sam Lantinga, Senior Software Engineer, Blizzard Entertainment