[racket] Reliably disable/redirect console output

On Mon, 2011-10-17 at 14:02 -0600, Ryan Culpepper wrote:
> It's possible that the output happens when the main module's requires 
> are executed. 

Actually, yes, it's just that. I guess I'm paying the price now for
having been a bit picky. Many of the initialization routines in my
modules deliberately use 'if' instead of 'when' and always return
values...

I have my own logging functions and would still like to redirect console
output but for the time being will focus on eliminating the return
values at the top level instead.

Thanks for the help to everyone!