Vittorio G.  to Eric, Sam

Actually this is much simpler than i thought, I just had to specify a
class method to get the delegate name and then the category can
override that method!
I've attached the patch that enables this features: in my code i could
remove my custom main() and simply add

@implementation SDLUIKitDelegate (customDelegate)
+(NSString *)getAppDelegateClassName {
   return @"HedgewarsAppDelegate";
}
@end

I tested it and with the sdl demos it loads the normal
SDLUIKitDelegate, while in my code it loads my HedgewarsAppDelegate!