* spot/twaalgos/cobuchi.cc, spot/twaalgos/cobuchi.hh (to_nca): New
function.
(weak_to_cobuchi): New internal function, used in to_nca and to_dca
when appropriate.
* spot/twaalgos/postproc.cc, spot/twaalgos/postproc.hh: Implement
the CoBuchi option.
* python/spot/__init__.py: Support it in Python.
* bin/common_post.cc: Add support for --buchi.
* bin/autfilt.cc: Remove the --dca option.
* tests/core/dca.test, tests/python/automata.ipynb: Adjust and add
more tests. In particular, add more complex persistence and
recurrence formulas to the list of dca.test.
* tests/python/dca.test: Adjust and rename to...
* tests/core/dca2.test: ... this. Add more tests, to the point
that this is now failing, as described in issue #317.
* tests/python/dca.py: Remove.
* tests/Makefile.am: Adjust.
* NEWS: Update.
* spot/twaalgos/cobuchi.hh: Declare to_dca() and nsa_to_nca().
* spot/twaalgos/cobuchi.cc: Implement them.
* python/spot/impl.i: Include new file for python bindings.
* spot/twaalgos/Makefile.am: Add new file.
* bin/autfilt.cc: Add --dca command line option. This option does not
return a deterministic automaton yet, but it will.
* tests/core/dca.test: Add tests for Büchi automata.
* tests/python/dca.py: Add a python script that builds a nondet. Streett
automaton.
* tests/python/dca.test: Add tests for Streett automata.
* tests/Makefile.am: Add all tests.
