to_parity: Improve to_parity and update tests

* spot/twaalgos/toparity.cc: Use a better search of the
transitions when we search compatible states.
* spot/twaalgos/toparity.hh: Use less that 80 columns.
* tests/python/merge.py, tests/python/toparity.py: Update tests.

tests/python/merge.py

@@ -78,7 +78,8 @@ assert hoa == """HOA: v1
 States: 3
 Start: 0
 AP: 2 "a" "b"
-Acceptance: 2 Fin(1) | Inf(0)
+acc-name: parity min even 2
+Acceptance: 2 Inf(0) | Fin(1)
 properties: trans-labels explicit-labels trans-acc
 --BODY--
 State: 0

tests/python/toparity.py

@@ -288,7 +288,7 @@ State: 4
 [0&!1] 4
 [0&1] 4 {1 2 4}
 --END--
-"""), [9, 6, 6, 6, 7, 6, 6])
+"""), [9, 6, 7, 7, 6, 6, 6])
 
 test(spot.automaton("""
 HOA: v1