EQness of numbers

[David.Dill@CMU-CS-A (L170DD60)]

I seem to have yielded to a personal prejudice against using EQ in
common-lisp outside of implementation-level code (see flames of last
year).  The issue of whether two numbers with the same value are always
EQ is indeed somewhat distinct from the issue of EQ preservation by
DEFCONSTANT.

Still, demanding EQL-equivalence but not EQ-equivalence provides the
maximum preservation of identity while not screwing compiler
optimizations.  Using EQ on numbers (correctly) will probably be
a relatively rare operation, which is not worth sacrificing generally
applicable compiler optimizations for.