event./univ. and syntactic implications rewriting in ltl_simplifier.
* 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.