Lunar DEFSETF

[Scott E. Fahlman <Fahlman@CMU-CS-C>]

It took a while (and some clarifying) for me to understand Dave Moon's
new DEFSETF proposal, but for the record I now believe that it is all
necessary and that nothing simpler will cut it.  Given the need for this
much complexity, Moon's solution is elegant: even hard-core users will
seldom have to deal directly with the general 5-value forms, since the
simpler forms are handled automatically, but the escape hatch is there
if they need it.  So I endorse this proposal.

I am still opposed to the inclusion of multiple new values, however.

-- Scott