It has two modes: strict or not. In strict mode (tested in
hoaparse.test), the acceptance formula has to match exactly the one
given in the HOA spec. In non-strict mode (tested in accparse2.py)
any equivalent formula is accepted.
* src/twa/acc.cc, src/twa/acc.hh (acc_cond::is_parity): New method.
* src/twaalgos/hoa.cc: Use it.
* src/tests/hoaparse.test: Test it.
* wrap/python/spot_impl.i: Bind it.
* wrap/python/tests/accparse2.py: New file.
* wrap/python/tests/Makefile.am: Add it.
