twa: add support for prop_complete()

* spot/twa/twa.hh: Add support.  Make two constructors for prop_set in
order to diagnose constructions with 5 arguments.
* spot/parseaut/parseaut.yy: Adjust diagnostics for complete and
deterministic.
* spot/tl/exclusive.cc, spot/twa/twagraph.cc,
spot/twaalgos/alternation.cc, spot/twaalgos/complete.cc,
spot/twaalgos/complete.hh, spot/twaalgos/degen.cc,
spot/twaalgos/determinize.cc, spot/twaalgos/hoa.cc,
spot/twaalgos/isdet.cc, spot/twaalgos/mask.cc,
spot/twaalgos/minimize.cc, spot/twaalgos/product.cc,
spot/twaalgos/remfin.cc, spot/twaalgos/remprop.cc,
spot/twaalgos/sbacc.cc, spot/twaalgos/sccfilter.cc,
spot/twaalgos/simulation.cc, spot/twaalgos/strength.cc,
spot/twaalgos/stutter.cc, spot/twaalgos/totgba.cc,
tests/core/parseaut.test, tests/python/product.ipynb: Adjust.
* NEWS, doc/org/concepts.org, doc/org/hoa.org,
doc/org/tut21.org: Document it.

spot/twaalgos/simulation.cc

@@ -595,6 +595,7 @@ namespace spot
                        { false, // state-based acc forced below
                          true,  // weakness preserved,
                          false, true, // determinism improved
+                         true, // completeness preserved
                          true, // stutter inv.
                        });
         // !unambiguous and !semi-deterministic are not preserved