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.
* doc/org/upgrade2.org: New file.
* doc/Makefile.am, doc/org/index.org: Add it.
* doc/org/tut22.org: Add some custom id for reference.
* doc/org/spot.css: Style the tables.
* NEWS: Mention the new doc.
* doc/org/concepts.org: New file.
* doc/Makefile.am: Add it.
* doc/org/oaut.org: Add anchor.
* doc/org/index.org, doc/org/tut.org: Add links to concepts.org.
* doc/org/spot.css: Set up boxes for implementation details.
* NEWS: Mention the new page.
* elisp/hoa-mode.el, elisp/Makefile.am, elisp/README: New files.
* debian/copyright, configure.ac, README, Makefile.am: Adjust.
* doc/org/init.el.in: Adjust to load hoa-mode.el.
* doc/org/spot.css: Add entries for HOA mode.
* doc/org/hoa.org, doc/org/ltldo.org, doc/org/oaut.org,
doc/org/tut20.org, doc/org/tut21.org, doc/org/tut22.org,
doc/org/tut30.org: Make the HOA outputs as HOA.