[racket] Support for R7RS-small?

What I saw of R7RS-small in a quick skim suggests that (unless I missed 
something hard) it could be done by an experienced programmer who was 
new to Racket, or by someone like a smart CS undergrad who will put in 
the hours to work through all the details.

You'll need some library procedures, some macros, some reader tweaks.  
And you always need to be careful with mutable pairs as you're expanding 
R7RS code to Racket code.  And possibly things I missed.

Someone should be encouraged to do this.  R7RS-small seems to be a 
return to the spirit of R5RS, and it would be a nice gesture to provide 
a "#lang r7rs-small", given that Scheme is family.  (I'm in the middle 
of redoing the Racket SICP support, myself.)

The only caution I have is that the documentation encourage people to 
use Racket unless they really know why they want to use R7RS.  I explain 
in earlier messages regarding R6RS:
http://lists.racket-lang.org/users/archive/2011-May/045444.html
http://lists.racket-lang.org/users/archive/2011-May/045456.html
http://lists.racket-lang.org/users/archive/2011-May/045461.html
http://lists.racket-lang.org/users/archive/2011-May/045448.html
http://lists.racket-lang.org/users/archive/2012-July/053088.html

Neil V.