* bench/stutter/stutter_invariance_randomgraph.cc: Update to recent
changes.  If an algorithm took more that 30s on an average for a set of
parameters, avoid running it with more states.  Take the density and
ap count as parameter.  Output all the algorithms on the same line.
Add additional statistics about automata.
* bench/stutter/stutter_invariance_formulas.cc: Update to recent
changes.  Output all the algorithms on the same line.
Add additional statistics about automata.
* bench/stutter/stutter_bench.sh: Use a Makefile to manage concurrency.
* bench/stutter/README: Update.