print_dot: improve the rendering of Mealy machines
- spot/twaalgos/dot.cc (print_dot): Add some detection of Mealy
machines, and some code to render its I/O in a
.
- tests/python/synthesis.ipynb: Adjust expected output.
- tests/python/_mealy.ipynb: New file.
- tests/Makefile.am: Add python/_mealy.ipynb.
- NEWS: Mention the new feature.