separate boot expansion from memoization
* libguile/Makefile.am:
* libguile/init.c:
* libguile/expand.c:
* libguile/expand.h: Add new expander. The idea is that macroexpansion
is one thing, and whether to compile or interpret the result of that
is another thing.
* libguile/memoize.c: Adapt to expand as necessary, and then memoize
expanded source without worrying about syntax errors.
* module/ice-9/eval.scm (make-general-closure): Allow alt clauses to not
possess the full make-general-closure arity.