cos -> goops, maybe not?

[Doug Evans]

I've been looking through r6rs (r6rs.org) and various Scheme 
implementations.

As far as moving to goops, the higher order bit to me is to be able to 
run cgen on multiple Scheme implementations.

I still think we should replace cos, or at least slim it down and 
simplify it (and keep it r5rs (or r6rs) compatible).
OTOH, it might be nice to have something that can advantage of the 
underlying data structure support of particular Scheme implementations, 
it would presumably help when printing objects for example.

Anyways,
fyi.