* spot/gen/automata.hh, spot/gen/automata.cc: Hide ks_cobuchi() behind
introduce aut_pattern(), as we have already done for the formulas.
* bin/genaut.cc: Simplify using this interface.
* python/spot/gen.i: Introduce aut_patterns().
* tests/python/gen.ipynb, tests/python/gen.py: Adjust.
* bin/genaut.cc: Use RANGE instead of N, and document it.
Output the FORMAT documentation, and fix handling of %F and %L.
* tests/core/genaut.test: New file.
* tests/Makefile.am: Add it.
Similarly to genltl that generates LTL formulas for various classes that
appear in the literature, genaut generates automata.
* NEWS: Mention the modification.
* bin/Makefile.am: Build the new binary.
* bin/genaut.cc: The new binary itself.
