Fix some memory leaks, and fix a bug: state 0 was examined twice.

Fix some memory leaks, and fix a bug: state 0 was examined twice.
* src/LR0.c (new_state): Merge into...
(state_list_append): this.
(new_states): Merge into...
(generate_states): here.
(set_states): Don't ensure a proper `errs' state member here, do it...
* src/conflicts.c (conflicts_solve): here.
* src/state.h, src/state.c: Comment changes.
(state_t): Rename member `shifts' as `transitions'.
Adjust all dependencies.
(errs_new): For consistency, also take the values as argument.
(errs_dup): Remove.
(state_errs_set): New.
(state_reductions_set, state_transitions_set): Assert that no
previous value was assigned.
(state_free): New.
(states_free): Use it.
* src/conflicts.c (resolve_sr_conflict): Don't use an `errs_t' as
temporary storage: use `errs' and `nerrs' as elsewhere.
(set_conflicts): Allocate and free this `errs'.