* src/ltlvisit/clone.hh (clone): Likewise.
* src/ltlvisit/destroy.cc (destroy): New const version.
* src/ltlvisit/destroy.hh (destroy): Likewise.
* src/tgba/tgbabddconcretefactory.cc
(tgba_bdd_concrete_factory::create_state,
tgba_bdd_concrete_factory::create_atomic_prop,
tgba_bdd_concrete_factory::promise): Clone new formulae.
* src/tgba/tgbabdddict.cc (tgba_bdd_dict::tgba_bdd_dict,
tgba_bdd_dict::~tgba_bdd_dict, tgba_bdd_dict::operator=): New methods
that clone and destroy formulae.
* src/tgbatest/ltl2tgba.test, src/tgbatest/ltl2tgba.cc: New files.
* src/tgbatest/Makefile.am (check_PROGRAMS): Add ltl2tgba.
(ltl2tgba_SOURCES): New variable.
(TESTS): Add ltl2tgba.test.