[plt-scheme] Ants from ICFP

The code for the simulator that I wrote is available here:

http://www.cs.grinnell.edu/~guhaarju/icfp2004-simulator-only.tar.bz2

I'll post the rest over the weekend.  The most important optimization 
is that I preprocess instructions running the simulation (i.e. I create 
10,000 * 2 procedures) so that I don't have to  lookup states.  I also 
avoid calls to WORLD-CELL, to convert the coordinates of a cell to a 
cell structure.  I store a reference to the actual structure as far as 
possible.

I'd be interested in seeing Alex Shinn's code, if possible.

-Arjun