Updated GOR1 (fixed the core algorithm to avoid useless re-scans of the same state).

Updated GOR1 (fixed the core algorithm to avoid useless re-scans of the same state).

Also, depth-first traversal was done in a slightly incorrect way:
we checked outgoing nodes for admissibility and pushed the corresponding
child states on stack all at once. This is not the same as checking
the first child and recursing into it, then checking the next child,
..., and so on (because we might discover the second child while exploring
the first, and admissiblitiy check for the second child *after* that
might yield false, while *before* exploring the first child it yielded
true).