Improve SCC simplification by removing implied acceptance conditions.
Spot 0.7.1 used to need 190 acceptance conditions to translate the 188 literature formulae. With this patch we are down to 185. That's not an impressive, but there are only ~20 formulae that require more than 1 acceptance conditions; hence little room for improvement. * src/misc/bddlt.hh (bdd_hash): New function. * src/misc/accconv.hh, src/misc/accconv.cc: New files. * src/misc/Makefile.am: Add them. * src/tgbaalgos/scc.cc (scc_map::build_map): Adjust to record all combination of acceptance conditions occurring in a SCC. * src/tgbaalgos/scc.hh (scc_map::scc::useful_acc): Update description. * src/tgbaalgos/sccfilter.cc (scc_filter): Simplify acceptance conditions that are always implied by another acceptance conditions. Previously, we only removed acceptance conditions that where always present in accepting SCCs. * src/tgbatest/sccsimpl.test: New file. * src/tgbatest/Makefile.am (TESTS): Add it.