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.
Operator &= used to always move Fin to the front, it does not anymore.
The only thing it does now is to merge Inf(x)&Inf(y) as Inf({x,y}).
Operator |= is now symmetrical and merges Fin()s.
Fixes#253.
* spot/twa/acc.cc, spot/twa/acc.hh: Simplify &= and make |= symmetrical.
* spot/twaalgos/cleanacc.cc: Fix conjunction order.
* tests/core/acc.test, tests/core/acc2.test, tests/core/parseaut.test,
tests/core/readsave.test, tests/core/satmin2.test,
tests/core/sccdot.test, tests/python/acc_cond.ipynb,
tests/python/accparse.ipynb, tests/python/automata.ipynb,
tests/python/product.ipynb, tests/python/randaut.ipynb: Adjust test
cases.
