File psl-1983/3-1/util/useful.build from the latest check-in

CompileTime load Useful;
in "backquote.sl"$
in "read-macros.sl"$
in "destructure.sl"$
in "cond-macros.sl"$
in "bind-macros.sl"$
in "set-macros.sl"$
in "iter-macros.sl"$
in "for-macro.sl"$
in "misc-macros.sl"$
in "macroexpand.sl"$