dualize: improve performance on small automata with large |AP|
For issue #566 (closed).
- spot/twaalgos/dualize.cc (dualizer::copy_edges): Implement another loop to be used when the number of outgoing edges of a state is smaller than the number of AP.
- tests/core/566.test: New file.
- tests/Makefile.am: Add it.
- NEWS: Mention the improvement.