* src/ltlvisit/simplify.hh
(ltl_simplifier::negative_normal_form): Allow logical
unabbreviations during the NNF pass.
* src/ltlvisit/simplify.cc
(ltl_simplifier::negative_normal_form)
(negative_normal_form_visitor): Adjust.
(ltl_simplifier::simplify): Request unabbreviations.
* src/ltlvisit/reduce.cc (reduce): Remove most
of the code, leaving only a call ltl_simplifier
and some wrapper code to convert options.
* src/ltltest/reduccmp.test: Add more test cases.