* NEWS: Update.
* spot/twaalgos/genem.cc, spot/twaalgos/genem.hh, spot/twa/twa.cc:
Update copyright years.
* spot/twa/twa.hh: Update Doxygen documentation.
* spot/twaalgos/sccinfo.cc, spot/twaalgos/sccinfo.hh: Simplify data
structures, and fix failure of get_accepting_run() to compute
accepting runs in SCC that are accepting due to the self-loop
optimization of scc_info.
* tests/python/highlighting.ipynb: Add three test cases.