Start porting Racket version to Racket style

Hi. I saw your request in the README to update the Racket version to idiomatic Racket, so I've started on that in this pull request. There's more that could be done, but it's a start.

To run the tests, use `raco test mk-rd.rkt` from the commandline or run it in DrRacket. It uses a `test` submodule that is only loaded in test mode.