dot: --dot=B to use bullets for all automata but Büchi and co-Büchi

* src/twaalgos/dotty.cc: Add option 'B'.
* src/taalgos/dotty.cc: Ignore it.
* src/bin/common_aoutput.cc, src/bin/dstar2tgba.cc: Document it.
* wrap/python/spot.py (setup): Use it by default, and rewrite
the function to be a bit more flexible.
* wrap/python/tests/automata-io.ipynb, wrap/python/tests/automata.ipynb,
wrap/python/tests/piperead.ipynb, wrap/python/tests/randaut.ipynb,
wrap/python/tests/testingaut.ipynb: Use setup() everywhere.

src/taalgos/dotty.cc

@@ -87,6 +87,7 @@ namespace spot
 	    case '1':
 	    case 'a':
 	    case 'b':
+	    case 'B':
 	    case 'n':
 	    case 'N':
 	    case 'o':