[plt-scheme] simulating cgi contexts in plt web server

Oh, I'm not going to use subprocesses, and I'm probably going to just 
get rid of the few places that environment variables are used.

YC wrote at 04/17/2010 03:09 PM:
> I asked about this in the thread 
> http://list.cs.brown.edu/pipermail/plt-scheme/2010-January/037711.html
>
> Basically PLT currently does not allow passing environment variables 
> to subprocesses so it won't work well with PLT threads.  The way 
> around it is to use `env` program on *nix platform but that will incur 
> one additional call.