Fixes #3.

* spot/tl/simplify.cc: Implement this new rule.
* doc/tl/tl.tex, NEWS: Document it.
* tests/core/reduccmp.test: Test it.

For #199.

* tests/sanity/style.test: Test this.
* bin/ltlcross.cc, spot/parseaut/parseaut.yy,
tests/ltsmin/modelcheck.cc: Fix it.

Fixes #319.

* spot/twaalgos/dot.cc: Enable "a" by default.
* bin/common_aoutput.cc, NEWS: Document it.
* doc/org/autfilt.org, doc/org/concepts.org, doc/org/dstar2tgba.org,
doc/org/hierarchy.org, doc/org/ltl2tgba.org, doc/org/oaut.org,
doc/org/randaut.org, doc/org/satmin.org, doc/org/tut23.org,
doc/org/tut24.org, doc/org/tut30.org, doc/org/tut31.org: Adjust or
simplify the documentation.
* tests/core/det.test, tests/core/dstar.test, tests/core/monitor.test,
tests/core/neverclaimread.test, tests/core/readsave.test,
tests/core/tgbagraph.test, tests/core/wdba.test,
tests/python/_autparserr.ipynb, tests/python/automata-io.ipynb,
tests/python/automata.ipynb, tests/python/highlighting.ipynb
tests/python/ltsmin-dve.ipynb, tests/python/ltsmin-pml.ipynb,
tests/python/product.ipynb, tests/python/testingaut.ipynb,
tests/python/word.ipynb: Adjust test cases.

* spot/twa/acc.cc: These functions were segfaulting on acceptance
conditions such as "Acceptance: 3 t" or "Acceptance: 3 f".
The issue was revealed on branch "next" by the change that print_dot()
display the acceptance condition by default, but we want the fix on
master as well.
* NEWS: Mention the issue.

Fixes #326.

* Makefile.am: Here.

Fixes #329.

* configure.ac: Do not check for lbt, modella, and ltl2nba.
* bench/ltl2tgba/defs.in: Remove the associated substitutions,
not used in the scripts.

* spot/misc/hashfunc.hh: make the definition of FNV hash magic constants
  more generic

* spot/misc/bitvect.cc, spot/misc/hashfunc.hh: move FNV hash function,
  use the new interface

* bin/autfilt.cc, bin/common_post.cc, spot/graph/graph.hh,
  spot/twa/twa.hh, spot/twa/twagraph.hh, spot/twaalgos/remfin.cc: typos
* spot/twaalgos/toweak.cc: incorrect types when invoking std::hash

* tests/core/ltl2dstar.test: Here.

* doc/Makefile.am: Here.

* NEWS: document it
* spot/twa/twagraph.hh, spot/twa/twagraph.cc: implement it
* tests/core/tgbagraph.test, tests/core/twagraph.cc: test it

* .dir-locals.el: Here.
* tests/core/remfin.test, tests/core/unambig.test:
Make consistent references to issue numbers.
* HACKING: Document convention for mentioning issues.

* .gitlab-ci.yml: Add a build with gcc-snapshot, and disable Debian
packages on all branches except master/next/stable and branches ending
in "-deb".

* spot/twaalgos/determinize.cc: the acceptance condition
  of the determinized automaton should be simpler
* tests/core/safra.test, tests/python/simstate.py: update tests

* spot/twaalgos/parity.cc: cleanup_parity and cleanup_parity_here are
  now better at finding useless parity colors
* tests/python/parity.py: test it
* NEWS: document the change

This helps working around missing C functions like strcasecmp that do
not exist everywhere (e.g. on Cygwin), and for which lib/ supplies a
replacement.  Unfortunately we do not have such build in our current
continuous integration suite, so we cannot easily detect files where
such config.h inclusion would be useful.  Therefore this patch simply
makes it mandatory to include config.h in *.cc files.  Including this
in public *.hh file is currently forbidden.

* spot/gen/automata.cc, spot/gen/formulas.cc,
spot/kripke/fairkripke.cc, spot/kripke/kripke.cc,
spot/ltsmin/ltsmin.cc, spot/misc/game.cc, spot/parseaut/fmterror.cc,
spot/parsetl/fmterror.cc, spot/parsetl/parsetl.yy,
spot/priv/bddalloc.cc, spot/priv/freelist.cc, spot/priv/satcommon.cc,
spot/priv/trim.cc, spot/priv/weight.cc, spot/ta/ta.cc,
spot/ta/taexplicit.cc, spot/ta/taproduct.cc, spot/ta/tgtaexplicit.cc,
spot/ta/tgtaproduct.cc, spot/taalgos/dot.cc,
spot/taalgos/emptinessta.cc, spot/taalgos/minimize.cc,
spot/taalgos/reachiter.cc, spot/taalgos/statessetbuilder.cc,
spot/taalgos/stats.cc, spot/taalgos/tgba2ta.cc, spot/tl/apcollect.cc,
spot/tl/contain.cc, spot/tl/declenv.cc, spot/tl/defaultenv.cc,
spot/tl/dot.cc, spot/tl/exclusive.cc, spot/tl/hierarchy.cc,
spot/tl/length.cc, spot/tl/ltlf.cc, spot/tl/mark.cc,
spot/tl/mutation.cc, spot/tl/nenoform.cc, spot/tl/print.cc,
spot/tl/randomltl.cc, spot/tl/relabel.cc, spot/tl/remove_x.cc,
spot/tl/simplify.cc, spot/tl/snf.cc, spot/tl/unabbrev.cc,
spot/twa/acc.cc, spot/twa/bdddict.cc, spot/twa/bddprint.cc,
spot/twa/formula2bdd.cc, spot/twa/taatgba.cc, spot/twa/twa.cc,
spot/twa/twagraph.cc, spot/twa/twaproduct.cc, spot/twaalgos/aiger.cc,
spot/twaalgos/alternation.cc, spot/twaalgos/are_isomorphic.cc,
spot/twaalgos/bfssteps.cc, spot/twaalgos/canonicalize.cc,
spot/twaalgos/cleanacc.cc, spot/twaalgos/cobuchi.cc,
spot/twaalgos/complement.cc, spot/twaalgos/complete.cc,
spot/twaalgos/compsusp.cc, spot/twaalgos/couvreurnew.cc,
spot/twaalgos/cycles.cc, spot/twaalgos/degen.cc,
spot/twaalgos/determinize.cc, spot/twaalgos/dot.cc,
spot/twaalgos/dtbasat.cc, spot/twaalgos/dtwasat.cc,
spot/twaalgos/dualize.cc, spot/twaalgos/emptiness.cc,
spot/twaalgos/gtec/ce.cc, spot/twaalgos/gtec/gtec.cc,
spot/twaalgos/gtec/sccstack.cc, spot/twaalgos/gtec/status.cc,
spot/twaalgos/gv04.cc, spot/twaalgos/hoa.cc,
spot/twaalgos/iscolored.cc, spot/twaalgos/isdet.cc,
spot/twaalgos/isunamb.cc, spot/twaalgos/isweakscc.cc,
spot/twaalgos/langmap.cc, spot/twaalgos/lbtt.cc,
spot/twaalgos/ltl2taa.cc, spot/twaalgos/ltl2tgba_fm.cc,
spot/twaalgos/magic.cc, spot/twaalgos/mask.cc,
spot/twaalgos/minimize.cc, spot/twaalgos/neverclaim.cc,
spot/twaalgos/parity.cc, spot/twaalgos/postproc.cc,
spot/twaalgos/powerset.cc, spot/twaalgos/product.cc,
spot/twaalgos/rabin2parity.cc, spot/twaalgos/randomgraph.cc,
spot/twaalgos/randomize.cc, spot/twaalgos/reachiter.cc,
spot/twaalgos/relabel.cc, spot/twaalgos/remfin.cc,
spot/twaalgos/remprop.cc, spot/twaalgos/sbacc.cc,
spot/twaalgos/sccfilter.cc, spot/twaalgos/sccinfo.cc,
spot/twaalgos/se05.cc, spot/twaalgos/sepsets.cc,
spot/twaalgos/simulation.cc, spot/twaalgos/split.cc,
spot/twaalgos/stats.cc, spot/twaalgos/strength.cc,
spot/twaalgos/stripacc.cc, spot/twaalgos/stutter.cc,
spot/twaalgos/sum.cc, spot/twaalgos/tau03.cc,
spot/twaalgos/tau03opt.cc, spot/twaalgos/totgba.cc,
spot/twaalgos/toweak.cc, spot/twaalgos/translate.cc,
spot/twaalgos/word.cc, tests/core/acc.cc, tests/core/bitvect.cc,
tests/core/checkpsl.cc, tests/core/checkta.cc, tests/core/consterm.cc,
tests/core/emptchk.cc, tests/core/equalsf.cc, tests/core/graph.cc,
tests/core/ikwiad.cc, tests/core/intvcmp2.cc, tests/core/intvcomp.cc,
tests/core/kind.cc, tests/core/kripkecat.cc, tests/core/length.cc,
tests/core/ltlrel.cc, tests/core/ngraph.cc, tests/core/parity.cc,
tests/core/randtgba.cc, tests/core/readltl.cc, tests/core/reduc.cc,
tests/core/safra.cc, tests/core/sccif.cc, tests/core/syntimpl.cc,
tests/core/taatgba.cc, tests/core/tostring.cc, tests/core/trival.cc,
tests/core/twagraph.cc, tests/ltsmin/modelcheck.cc,
spot/parseaut/scanaut.ll, spot/parsetl/scantl.ll: Include config.h.
* spot/gen/Makefile.am, spot/graph/Makefile.am,
spot/kripke/Makefile.am, spot/ltsmin/Makefile.am,
spot/parseaut/Makefile.am, spot/parsetl/Makefile.am,
spot/priv/Makefile.am, spot/ta/Makefile.am, spot/taalgos/Makefile.am,
spot/tl/Makefile.am, spot/twa/Makefile.am, spot/twaalgos/Makefile.am,
spot/twaalgos/gtec/Makefile.am, tests/Makefile.am: Add the -I lib/
flags.
* tests/sanity/includes.test: Catch missing config.h in *.cc, and
diagnose config.h in *.hh.
* tests/sanity/style.test: Better diagnostics.

* NEWS, configure.ac: Here.

* NEWS, configure.ac, doc/org/setup.org: Set version to 2.5.1.

* doc/org/install.org: Point to the gitlab-ci artefacts.

The bug is mentioned by Maximilien Colange in a comment to issue #317,
but turned out to be unrelated to that original issue.

* spot/twaalgos/totgba.cc (dnf_to_streett): Save the correspondence
between the created states an the DNF clause in a named property.
* doc/org/concepts.org, spot/twaalgos/totgba.hh: Mention the new
property.
* spot/twaalgos/cobuchi.cc (save_inf_nca_st): Rewrite using the named
property.  Relying on seen marks and trying to deduce the matching
original clause could only work from plain Rabin.
* tests/core/dca.test: Add the test from Maximilien.
* NEWS: Mention the issue.

* spot/twaalgos/cobuchi.cc, spot/twaalgos/totgba.cc: Here.

Fixes #324, reported by Tobias Meggendorfer and František Blahoudek.

* spot/twa/acc.hh (rs_pairs_view::paired_with): Rename as...
(rs_pairs_view::paired_with_fin):... this and adjust the code.
* spot/twaalgos/remfin.cc: Use paired_with_fin instead of
paired_with, and do it once per pair.
* tests/core/remfin.test: Add a test case.
* NEWS: Mention the issue.

* spot/twaalgos/cleanacc.cc (merge_identical_marks_here): Do not call
cleanup_acceptance_here(), as this has already been done.

Fixes #325.

* spot/twa/acc.cc: Here.
* tests/core/accsimpl.test: New test case.
* NEWS: Mention the issue.

* tests/python/otfcrash.py: Remove the file generated by divine.

spot::iar() was fixed to handle correctly Rabin-like conditions.
It also now supports Streett-like conditions.

* NEWS, spot/twaalgos/postproc.cc: document it
* spot/twaalgos/rabin2parity.cc, spot/twaalgos/rabin2parity.hh:
  implement it
* tests/core/rabin2parity.test, tests/python/except.py: test it

Fixes #320.

* spot/twaalgos/totgba.cc: Fix the bug.
* NEWS: Mention the problem.
* tests/core/streett.test: Add test case.

* NEWS, configure.ac, doc/org/setup.org: Bump version.

* tests/python/ipnbdoctest.py: Adjust to Python <3.6.
* tests/python/_autparserr.ipynb: Adjust to older IPython version.
* tests/python/stutter-inv.ipynb: Avoid pandas because its output
varies from version to version.