acc: recognize parity acceptance

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.

src/twaalgos/hoa.cc

@@ -328,6 +328,16 @@ namespace spot
 		      os << ' ' << p;
 		    os << nl;
 		  }
+		else
+		  {
+		    bool max = false;
+		    bool odd = false;
+		    if (aut->acc().is_parity(max, odd))
+		      os << "acc-name: parity "
+			 << (max ? "max " : "min ")
+			 << (odd ? "odd " : "even ")
+			 << num_acc << nl;
+		  }
 	      }
 	  }
       }