* src/tgbaalgos/stripacc.cc, src/tgbaalgos/stripacc.hh: New files.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgbaalgos/postproc.cc, src/tgbaalgos/postproc.hh: Add a Monitor
output option.
* src/bin/ltl2tgba.cc: Add a --monitor/-M option.
* NEWS: Mention monitors.
* src/tgba/tgbaexplicit.hh (is_accepting_state): Fix for the
case where the automaton has no acceptance set.
