[racket] application-file-handler problem on OS X

At Fri, 09 Sep 2011 16:18:07 +0100, Erich Rast wrote:
> 
> 
> > How about a new `application-started-empty-handler' parameter for a
> > function that is called only when the `application-file-handler'
> 
> That would be great! All I need is a means to get the standard start
> behavior of graphical applications on OS X. 

I've added `application-start-empty-handler'.

Along the way, I think I also fixed a problem where startup files
sometimes get lost on Mac OS X.