SETF/PUSH/POP and LISP;NEW RECENT

[RWK at MIT-MC (Robert W. Kerns)]

OK, I've fixed SETF/PUSH/POP WRT order of evaluation.  Works like a charm.

I've also update muchly LISP;NEW RECENT.  You should have a look at it.
I probably say too much about PUSH/POP/SETF, but I couldn't think of any way
to concisely specify the properties that these are guarenteed to have, without
also being obscure.  I also documented PROG1, since I made XC understand it.