twaalgos/totgba: Add dnf_to_streett() method

* NEWS: Update.
* spot/twaalgos/totgba.hh: Declare dnf_to_streett().
* spot/twaalgos/totgba.cc: Implement dnf_to_streett().
* bin/autfilt.cc: Add --dnf-to-streett cmd line option.
* tests/core/dnfstreett.test: Add test.
* tests/Makefile.am: Add test file.

NEWS

@@ -9,6 +9,10 @@ New in spot 2.4.0.dev (not yet released)
     --ms-phi-r=RANGE       (FGa{n}&GFb{n})|((FGa{n-1}|GFb{n-1})&(...))
     --ms-phi-s=RANGE       (FGa{n}|GFb{n})&((FGa{n-1}&GFb{n-1})|(...))
 
+  - autfilt learned --streett-like to convert an automaton in order to
+    have a Streett-like acceptance condition. It only works with
+    ω-automata having an acceptance in disjunctive normal form.
+
   Library:
 
   - Rename three methods of spot::scc_info. New names are clearer. The
@@ -26,6 +30,11 @@ New in spot 2.4.0.dev (not yet released)
     recognize more if the original language can not be expressed with
     a co-Büchi acceptance condition.
 
+  - The new function dnf_to_streett() is able to convert any automaton
+    with an acceptance condition in Disjunctive Normal Form to a
+    Streett-like automaton. This is used by the new option
+    '--streett-like' of autfilt.
+
   Deprecation notices:
 
   (These functions still work but compilers emit warnings.)