* bin/common_ioap.cc, bin/common_ioap.hh (read_part_file): New
function.
* bin/ltlfilt.cc, bin/ltlmix.cc, bin/ltlsynt.cc: Use it.
* doc/org/ltlfilt.org, doc/org/ltlmix.org, doc/org/ltlsynt.org:
Mention that new option, and improve the links to its description
in ltlsynt.org.
* NEWS: Mention the new option.
* tests/core/ltlfilt.test, tests/core/ltlmix.test,
tests/core/ltlsynt.test: Adjust test cases.
* bin/ltlmix.cc: Add options --ins, --outs, as well as the
two-argument form of -A/-P.
* bin/common_ioap.hh, bin/common_ioap.cc (is_output): New function.
* spot/tl/apcollect.cc, spot/tl/apcollect.hh (create_atomic_prop_set):
Allow the prefix string to be changed.
* spot/tl/randomltl.cc, spot/tl/randomltl.hh: Add support for an I/O
version with two set of atomic proposition, and a predicate to decide
if the original proposition was input or output.
* tests/core/ltlmix.test: More tests.
Fixes#400.
* spot/tl/randomltl.cc, spot/tl/randomltl.hh: Adjust to accept
a set of formula to replace the atomic propositions.
* bin/ltlmix.cc: New file.
* bin/Makefile.am: Add it.
* bin/man/ltlmix.x: New file.
* bin/man/Makefile.am: Add it.
* doc/org/ltlmix.org: New file.
* doc/Makefile.am: Add it.
* bin/man/genltl.x, bin/man/randltl.x, bin/man/spot.x, bin/spot.cc,
doc/org/arch.tex, doc/org/concepts.org, doc/org/tools.org, NEWS: Mention
ltlmix.
* tests/core/ltlmix.test: New file.
* tests/Makefile.am: Add it.
