Number states using negative values and SCCs using nonnegative
values. Before this change states were numbered using positive values and SCCs using negative values. That meant the user had to work with negative values. With this changes, the nonnegative values used to label SCCs can also directly be used as index in the scc_map_. * src/tgbaalgos/scc.hh (scc_map::scc_of_state, scc_map::cond_set_of, scc_map::acc_set_of, scc_map::states_of, scc_map::initial, scc_map::scc_type, scc_map::succ, scc_map::accepting): Adjust prototypes to take or return unsigned arguments. * src/tgbaalgos/scc.cc: Adjust prototypes of the above functions. (scc_map::build_map, scc_map::relabel_component): Number states using negative values, and SCCs using nonnegative values. (dump_scc_dot): Adjust to use nonnegative values.