* src/tgba/tgbagraph.cc (purge_dead_states): Using a DFS to compute a
topological order, allowing to remove useless using a second
pass (instead of iterating the passes until there is nothing to remove).
* src/tgbaalgos/remfin.cc: Call purge_dead_states().
* src/tgbatest/remfin.test, src/tgbatest/det.test: Adjust expected
output.
* doc/org/autfilt.org: Update example.