* 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.