[plt-scheme] xxx chooses MzScheme as preferred language

Matthew Flatt wrote:
> My main conclusion: if someone wants to improve the MzScheme results,
> consider starting with the Chicken code (and dump mzc after v301).

Matthew's conclusion seems to be supported by the test data.  I reran the tests
using MzScheme 301.16, which I then compared with mzc:

"http://shootout.alioth.debian.org/sandbox/benchmark.php?test=all〈=mzscheme&lang2=mzc"

As you can see, MzScheme meets or exceeds MzC in all cases, although its
memory use is often a bit higher.

MzScheme is still quite a bit slower than Chicken, but the results are far better
than my initial impression, in the 2-5x range, rather than orders of magnitude:

"http://shootout.alioth.debian.org/sandbox/benchmark.php?test=all〈=mzscheme&lang2=chicken"

I'll attempt to port the other tests over the next few days.  Eventually, it would
be nice to get a bit of code review to see if there are any native MzScheme
features that might improve performance.

Thanks,

-Brent