* src/ltlvisit/reduce.cc (reduce_visitor): Move ...
* src/ltlvisit/simplify.cc (simplify_visitor): ... here, and
adjust to use the new ltl_simplifier_options.
* src/ltlvisit/reduce.cc (reduce): Use ltl_simplifier
to perform the work of reduce_visitor.  Eventually we want to
get rid of reduce.cc.
* src/ltlvisit/reduce.hh (reduce): Remove the
syntactic_implication_cache used as third argument.