[CM] Bug with sort

[bil at ccrma.Stanford.EDU]

I'm thinking of adding (*s7* 'scheme-version) which
could be 's7 (the default), 'r5rs, or 'r7rs.  In the
latter two, eq? would be a synonym for eqv? (and
also memq->memv and assq->assv), and in r7rs, I'd
pre-include r7rs.scm as a sort of resource and
load_c_string it if r7rs is requested.  Currently
you have to laboriously find that file and load it.

I also want to include repl.scm as a similar resource,
and have a way to get that repl built-in so that
you can call s7 anywhere and it will just work.
The current default (the "dumb" repl) is only
tolerable if you're using s7 in emacs.