[racket] Changing the pretty print columns when running raco expand

At Thu, 7 Nov 2013 08:39:41 -0800, Eric Dobson wrote:
> I use raco expand a bunch when debugging macros to see the final
> output and see why it doesn't match up with my expectations. One issue
> I have is that the pretty printer decides to only use 80ish columns
> when my terminal is 200 wide, this makes the output really ugly and
> hard to read. If this was a racket command I could use -e
> "(pretty-print-colums 200)", but I don't see a way to do that with
> raco. Is there an easy way to set up printing parameters before the
> expansion code is run?

I've added a `--columns <n>` (shorthand `-n <n>`) argument to `raco
expand` and `raco decompile`.