Fixes#311.
* tests/python/ipnbdoctest.py: Adjust to process the new format,
with a lot of inspiration from Vcsn's copy of this file.
* tests/python/_altscc.ipynb, tests/python/_aux.ipynb,
tests/python/acc_cond.ipynb, tests/python/accparse.ipynb,
tests/python/alternation.ipynb, tests/python/atva16-fig2a.ipynb,
tests/python/atva16-fig2b.ipynb, tests/python/automata-io.ipynb,
tests/python/automata.ipynb, tests/python/decompose.ipynb,
tests/python/formulas.ipynb, tests/python/gen.ipynb,
tests/python/highlighting.ipynb, tests/python/ltsmin-dve.ipynb,
tests/python/ltsmin-pml.ipynb, tests/python/parity.ipynb,
tests/python/piperead.ipynb, tests/python/product.ipynb,
tests/python/randaut.ipynb, tests/python/randltl.ipynb,
tests/python/stutter-inv.ipynb, tests/python/testingaut.ipynb,
tests/python/word.ipynb: Upgrade to the new format.
* NEWS: Mention the change.
* spot/twa/acc.cc, spot/twa/acc.hh: Add a LaTeX output for acceptance
conditions.
* spot/twaalgos/dot.cc: Implement the 'x' option and refactor the code
a bit to limit duplication.
* tests/core/dot2tex.test: New test case (requires dot2tex).
* tests/Makefile.am: Add dot2tex.test.
* tests/core/alternating.test, tests/core/readsave.test,
tests/python/automata-io.ipynb: Adjust expected output.
* NEWS, doc/org/oaut.org: Mention the new option.
This fixes the output gliches visible in the previous patches,
where highlighting a state would remove its fill color.
* spot/twaalgos/dot.cc, spot/taalgos/dot.cc: Implement option C(COLOR).
* bin/common_aoutput.cc, doc/org/oaut.org: Document it.
* doc/org/.dir-locals.el.in, doc/org/init.el.in,
python/spot/__init__.py: Use it.
* tests/python/automata-io.ipynb, tests/python/automata.ipynb,
tests/python/highlighting.ipynb: Test it.
* tests/core/readsave.test: Adjust.
* NEWS: Mention recent changes.
