* spot/graph/graph.hh, spot/twa/twagraph.hh, spot/twa/twagraph.cc:
Implement a dump_storage_as_dot() method.
* python/spot/__init__.py (twa_graph.show_storage): New method, above
dump_storage_as_dot().
* tests/python/twagraph-internals.ipynb: New file, with documentation
about the twa_graph internals, using show_storage() to illustrate
everything.
* tests/Makefile.am, doc/org/tut.org: Add it.
* python/spot/impl.i: Add bindings for out_iterasor, demonstrated in
the Python notebook.
* spot/twa/twa.hh: Add prop_reset(). Used in the notebook.
* NEWS: Mention the new notebook and function.
* doc/org/tut50.org: Link to the notebook.
* tests/python/ipnbdoctest.py: Adjust for twa_graph_ptr being
redefined in the spot namespace.
Suggested in #299.
* doc/org/autfilt.org, doc/org/concepts.org, doc/org/dstar2tgba.org,
doc/org/genaut.org, doc/org/hierarchy.org, doc/org/hoa.org,
doc/org/ltl2tgba.org, doc/org/ltl2tgta.org, doc/org/ltlcross.org,
doc/org/oaut.org, doc/org/randaut.org, doc/org/satmin.org,
doc/org/tut11.org, doc/org/tut23.org, doc/org/tut24.org,
doc/org/tut30.org, doc/org/tut31.org, doc/org/tut50.org,
doc/org/tut51.org: Adjust all dot outputs to produce svg.
* doc/org/arch.tex, doc/org/hierarchy.tex, doc/org/satmin.tex: Adjust
to produce a pdf with 12pt text.
* doc/Makefile.am: Adjust the generation of arch.svg, hierarchy.svg,
and satmin.svg: From above.
* doc/org/.dir-locals.el.in, doc/org/init.el.in: Adjust dot arguments
to produce svg with 12pt text (the default was 14pt).
* doc/org/spot.css: Use Lato as the main font for consistency with
automata.
* HACKING: pdf2svg is now required to build the doc.
