A tgba can now annotate a transition (i.e., the position of a

tgba_succ_iterator) with some string.  This comes handy to
associate that transition to its high-level name.
* src/tgba/tgba.hh, src/tgba/tgba.cc (tgba::transition_annotation):
New method.
* src/tgba/tgbaproduct.hh, src/tgba/tgbaproduct.cc
(tgba_product::transition_annotation): Implement it.
* src/tgba/tgbatba.hh, src/tgba/tgbatba.cc
(tgba_tba_proxy::transition_annotation): Likewise.
* src/tgbaalgos/replayrun.cc (print_annotation): New function.
(replay_tgba_run): Use it.

src/tgba/tgba.cc

@@ -69,4 +69,10 @@ namespace spot
     return 0;
   }
 
+  std::string
+  tgba::transition_annotation(const tgba_succ_iterator*) const
+  {
+    return "";
+  }
+
 }