Automatic mass renaming.

* src/tgbaalgos/: Rename as...
* src/twaalgos/: ... this.
* README, configure.ac, iface/ltsmin/modelcheck.cc, src/Makefile.am,
src/bin/autfilt.cc, src/bin/common_aoutput.cc,
src/bin/common_aoutput.hh, src/bin/common_output.hh,
src/bin/common_post.hh, src/bin/dstar2tgba.cc, src/bin/ltl2tgba.cc,
src/bin/ltl2tgta.cc, src/bin/ltlcross.cc, src/bin/ltldo.cc,
src/bin/ltlfilt.cc, src/bin/randaut.cc, src/dstarparse/dra2ba.cc,
src/dstarparse/nra2nba.cc, src/dstarparse/nsa2tgba.cc,
src/graphtest/twagraph.cc, src/kripke/kripkeprint.cc,
src/ltlvisit/contain.cc, src/ltlvisit/contain.hh,
src/ltlvisit/exclusive.cc, src/taalgos/emptinessta.hh,
src/tgbatest/checkpsl.cc, src/tgbatest/checkta.cc,
src/tgbatest/complementation.cc, src/tgbatest/emptchk.cc,
src/tgbatest/ltl2tgba.cc, src/tgbatest/ltlprod.cc,
src/tgbatest/randtgba.cc, src/tgbatest/taatgba.cc, src/twa/twa.cc,
src/twa/twagraph.hh, src/twa/twasafracomplement.cc,
wrap/python/spot_impl.i: Adjust.

Automatic mass renaming.

* src/bin/autfilt.cc, src/bin/common_aoutput.cc,
src/bin/common_aoutput.hh, src/bin/common_conv.cc,
src/bin/common_conv.hh, src/bin/common_output.hh, src/bin/dstar2tgba.cc,
src/bin/ltlcross.cc, src/bin/ltldo.cc, src/bin/randaut.cc,
src/dstarparse/dra2ba.cc, src/dstarparse/dstar2tgba.cc,
src/dstarparse/dstarparse.yy, src/dstarparse/nra2nba.cc,
src/dstarparse/nsa2tgba.cc, src/dstarparse/public.hh,
src/graphtest/tgbagraph.cc, src/hoaparse/hoaparse.yy,
src/hoaparse/public.hh, src/ltlvisit/contain.hh,
src/ltlvisit/exclusive.cc, src/ltlvisit/exclusive.hh,
src/priv/accmap.hh, src/taalgos/minimize.cc, src/tgba/fwd.hh,
src/tgba/tgba.cc, src/tgba/tgbagraph.cc, src/tgba/tgbagraph.hh,
src/tgba/tgbasafracomplement.cc, src/tgba/tgbasafracomplement.hh,
src/tgbaalgos/are_isomorphic.cc, src/tgbaalgos/are_isomorphic.hh,
src/tgbaalgos/canonicalize.cc, src/tgbaalgos/canonicalize.hh,
src/tgbaalgos/cleanacc.cc, src/tgbaalgos/cleanacc.hh,
src/tgbaalgos/complete.cc, src/tgbaalgos/complete.hh,
src/tgbaalgos/compsusp.cc, src/tgbaalgos/compsusp.hh,
src/tgbaalgos/cycles.hh, src/tgbaalgos/degen.cc, src/tgbaalgos/degen.hh,
src/tgbaalgos/dotty.cc, src/tgbaalgos/dtbasat.cc,
src/tgbaalgos/dtbasat.hh, src/tgbaalgos/dtgbacomp.cc,
src/tgbaalgos/dtgbacomp.hh, src/tgbaalgos/dtgbasat.cc,
src/tgbaalgos/dtgbasat.hh, src/tgbaalgos/dupexp.cc,
src/tgbaalgos/dupexp.hh, src/tgbaalgos/emptiness.cc,
src/tgbaalgos/emptiness.hh, src/tgbaalgos/hoa.cc,
src/tgbaalgos/isdet.cc, src/tgbaalgos/isdet.hh, src/tgbaalgos/lbtt.cc,
src/tgbaalgos/ltl2tgba_fm.cc, src/tgbaalgos/ltl2tgba_fm.hh,
src/tgbaalgos/mask.cc, src/tgbaalgos/mask.hh, src/tgbaalgos/minimize.cc,
src/tgbaalgos/minimize.hh, src/tgbaalgos/neverclaim.cc,
src/tgbaalgos/postproc.cc, src/tgbaalgos/postproc.hh,
src/tgbaalgos/powerset.cc, src/tgbaalgos/powerset.hh,
src/tgbaalgos/product.cc, src/tgbaalgos/product.hh,
src/tgbaalgos/randomgraph.cc, src/tgbaalgos/randomgraph.hh,
src/tgbaalgos/randomize.cc, src/tgbaalgos/randomize.hh,
src/tgbaalgos/relabel.cc, src/tgbaalgos/relabel.hh,
src/tgbaalgos/remfin.cc, src/tgbaalgos/remfin.hh,
src/tgbaalgos/remprop.cc, src/tgbaalgos/remprop.hh,
src/tgbaalgos/safety.cc, src/tgbaalgos/safety.hh,
src/tgbaalgos/sbacc.cc, src/tgbaalgos/sbacc.hh,
src/tgbaalgos/sccfilter.cc, src/tgbaalgos/sccfilter.hh,
src/tgbaalgos/sccinfo.cc, src/tgbaalgos/sccinfo.hh,
src/tgbaalgos/simulation.cc, src/tgbaalgos/simulation.hh,
src/tgbaalgos/stats.cc, src/tgbaalgos/stats.hh,
src/tgbaalgos/stripacc.cc, src/tgbaalgos/stripacc.hh,
src/tgbaalgos/stutter.cc, src/tgbaalgos/stutter.hh,
src/tgbaalgos/totgba.cc, src/tgbaalgos/totgba.hh,
src/tgbaalgos/translate.cc, src/tgbaalgos/translate.hh,
src/tgbatest/checkpsl.cc, src/tgbatest/complementation.cc,
src/tgbatest/emptchk.cc, src/tgbatest/ltl2tgba.cc,
src/tgbatest/randtgba.cc, wrap/python/spot_impl.i,
wrap/python/tests/automata-io.ipynb, wrap/python/tests/automata.ipynb,
wrap/python/tests/piperead.ipynb, wrap/python/tests/testingaut.ipynb:
Rename tgba_digraph as twa_graph.

Now that we support any type of omega-accetpance, not just "Generalized
Büchi", it is time to move away from GB and replace it by "ω", written
just w in ASCII.

This just change the name of the tgba class.  This part has to be done
by hand because the word "tgba" occurs in many contexts and a mass
replacement would be wrong.

This will be followed by some automatic renaming of all the derived
types and more.

* src/bin/autfilt.cc, src/bin/randaut.cc, src/kripke/fairkripke.hh,
src/ta/tgta.cc, src/ta/tgta.hh, src/tgba/fwd.hh, src/tgba/taatgba.cc,
src/tgba/taatgba.hh, src/tgba/tgba.cc, src/tgba/tgba.hh,
src/tgba/tgbagraph.hh, src/tgba/tgbaproduct.cc, src/tgba/tgbaproduct.hh,
src/tgba/tgbaproxy.cc, src/tgba/tgbaproxy.hh,
src/tgba/tgbasafracomplement.cc, src/tgba/tgbasafracomplement.hh,
src/tgbaalgos/are_isomorphic.cc, src/tgbaalgos/cleanacc.cc,
src/tgbaalgos/dotty.cc, src/tgbaalgos/dupexp.cc,
src/tgbaalgos/dupexp.hh, src/tgbaalgos/hoa.cc,
src/tgbaalgos/neverclaim.cc, src/tgbaalgos/simulation.cc,
src/tgbaalgos/stutter.cc, src/tgbatest/checkpsl.cc,
src/tgbatest/emptchk.cc, src/tgbatest/ltl2tgba.cc, wrap/python/spot.py,
wrap/python/spot_impl.i: Rename the tgba class into twa.

And add a cleanup_acceptance() version that copies.

* src/tgbaalgos/cleanacc.cc, src/tgbaalgos/cleanacc.hh: Rename
and add the second version.
* src/bin/autfilt.cc, src/bin/ltlcross.cc,
src/tgbaalgos/dtgbacomp.cc, src/tgbaalgos/remfin.cc: Use
cleanup_acceptance_here.

Sometimes, simplifying the acceptance condition (because it refers to
sets that do not appear in the automaton) cause more sets to be removed
from the acceptance condition, and therefore warrant another pass to
remove those sets from the automaton.

* src/tgbaalgos/cleanacc.cc: Here.
* src/tgbatest/hoaparse.test: Add a test case.

* src/tgba/acc.cc, src/tgba/acc.hh: Move the strip() routine from
acc_cond into acc_cond::mark_t, and the strip() routine from
cleanacc.cc into acc_cond::acc_code.  Introduce helper functions
to create inf()/fin()/t()/f() at the acc_code level.
* src/tgbaalgos/cleanacc.cc: Simplify, using the strip() function
from acc_code.
* src/tgbaalgos/mask.cc (mask_acc_sets): Use the strip() function
from acc_code so that it work on non-Buchi acceptance.
* src/tgbatest/maskacc.test: Add a test for the latter change.
* src/tgbaalgos/sccfilter.cc, src/tgbatest/acc.cc: Adjust the
use mark_t::strip().

* src/tgbaalgos/cleanacc.cc, src/tgbaalgos/cleanacc.hh: New file.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgba/acc.hh, src/tgba/tgba.hh (get_acceptance): Return a
reference.
* src/bin/autfilt.cc: Add a --cleanup-acceptance option.
* src/tgbatest/hoaparse.test: Test it.