[racket] zsh completions

I've written zsh completion specifications for the complete racket and
raco command lines (all 500 of them), and will push to the repository
soon.  If you're using zsh, then get it at

  http://tmp.barzilay.org/_racket

and see the installation instructions at the top.

If you're using bash, then you can use this after a quick use of
"chsh".  (But more seriously, zsh provides explanations for the
options, and tells you the name of the argument that it's completing
now, and about 17k other features.  Just run zsh to try this out...)

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!