* src/tgba/tgbagraph.hh, src/tgba/tgbagraph.cc: Add a copy constructor,
and some method to purge unreachable states.
* src/graph/graph.hh (defrag_states): Erase transition of removed
states.
* src/tgbaalgos/complete.cc, src/tgbaalgos/compsusp.cc,
src/tgbaalgos/dtgbacomp.cc, src/tgbaalgos/simulation.cc,
src/tgbatest/checkpsl.cc, src/tgbatest/emptchk.cc,
src/tgbatest/ltl2tgba.cc: Adjust to use make_tgba_digraph() instead
of tgba_dupexp_dfs() or tgba_dupexp_bfs().
* src/tgbaalgos/dupexp.cc, src/tgbaalgos/dupexp.hh: Use
make_tgba_digraph() when possible.
* src/tgbatest/det.test, src/tgbatest/sim.test: Adjust expected results.
923785f76a