Together with the previous patch, this Fixes#353.
Implementing this required to extend our interface two support
two-parameter patterns.
* spot/gen/formulas.cc, spot/gen/formulas.hh: Implement it.
* bin/genltl.cc: Add --sejk-f.
* bin/common_output.cc, bin/common_output.hh: Adjust to handle
"line numbers" that are not integers (e.g., "3,2"), since those
are used to display pattern parameters.
* bin/ltlfilt.cc: Adjust.
* python/spot/gen.i: Add support for two-parameters patterns.
* tests/core/genltl.test, tests/python/gen.ipynb: Augment.
* NEWS: Mention it.
* spot/tl/hierarchy.hh, spot/tl/hierarchy.cc (nesting_depth): New
function.
* python/spot/__init__.py: Also make it a method of formula in Python
* bin/common_output.cc, bin/common_output.hh: Implement
--stats=%[OP]n.
* NEWS: Mention it.
* tests/core/format.test, tests/python/formulas.ipynb: Test it.
* bin/common_aoutput.cc, bin/common_aoutput.hh, bin/common_output.cc,
bin/common_output.hh: Add options to %x to list atomic propositions
with various quoting scheme. Deprecate --format=%a in favor of the
new --format=%x for consistency with --stats=%x.
* tests/core/format.test, tests/core/remprop.test: Adjust and add more
tests.
* NEWS: Mention these changes.
Tools for deciding the class of a formula.
* spot/tl/hierarchy.cc, spot/tl/hierarchy.hh: New files.
* spot/tl/Makefile.am: Add them.
* bin/common_output.cc, bin/common_output.hh: Implement --format=%h.
* tests/core/hierarchy.test: More tests.
* NEWS: Update.
