[plt-scheme] xxx chooses MzScheme as preferred language

Eli wrote:
> 2. Last time I checked, there was room for improving some of the code.
>   (But I remember much more code, so maybe things changed?)

We've been revising the shootout tests to make them a bit more realistic in terms of the tasks they perform,
as well as trying to make it harder for smart compilers like GHC to toss aside useless computations.  A
view of the original shootout tests are available here:

http://shootout.alioth.debian.org/old/benchmark.php?test=all〈=mzscheme&lang2=python

As far as the implementations go, I'm sure there is room for improvement -- I'm no expert with Scheme, though
I am learning...

-Brent