Get rid of the output in Spot's format.
This finally fixes#1.
* src/tgbaalgos/save.cc, src/tgbaalgos/save.hh: Delete.
* src/tgbaalgos/Makefile.am: Adjust.
* src/ltlvisit/contain.cc: Remove useless includes.
* src/bin/dstar2tgba.cc, src/bin/common_aoutput.cc,
src/bin/common_aoutput.hh: Remove the "Spot" output.
* doc/org/dstar2tgba.org, doc/org/ioltl.org,
doc/org/ltl2tgba.org, doc/org/oaut.org: Update doc.
* NEWS: Mention that Spot i/o is gone.
* src/tgbatest/randtgba.cc: Output in HOA.
* src/tgbatest/randtgba.test: Use randaut instead of
randtgba.
* wrap/python/spot.i: Do not provide binding for save.hh