[racket] Racket Syntax Highlighting for GeSHi

Folks,

I've just committed a first release of a GeSHi "plugin" for racket.
I believe that I can get it merged into GeSHi via the Rosetta Code
folks; it'll be nice to have racket highlighting in Media Wiki
(especially after Asumu's call to arms with R.C.)!

https://github.com/tim-brown/geshi-racket.git

Look for "racket.php" in this directory.
The "geshi-test.php" script is set up for you to have a GeSHi
installation in the current directory; but that's not included in the
git repository.

My only "difficult" issue is '|piped symbols with spaces| symbol
matching. I've given up wrestling with pattern matching and pipes.
(I think GeSHi temporarily creates "HTML" tags with <|element|> which
then mucks things up royally).

Any comments gratefully received, though.

Tim