* src/bin/common_cout.cc, src/bin/common_cout.hh: New files.
* src/bin/Makefile.am: Add them.
* src/bin/ltl2tgba.cc, src/bin/ltlfilt.cc, src/bin/common_output.cc:
Report error when writing to std::cout failed. This is mainly
motivated by ltlfilt not being killed by SIGPIPE on lip6's OSX
buildfarm (SIGPIPE is probably ignored when the build is started), but
it could detect other errors such as a disk full.
* src/bin/common_sys.hh: New file.
* src/bin/Makefile.am: Add it.
* src/bin/common_output.hh, src/bin/common_r.cc,
src/bin/common_range.cc, src/bin/genltl.cc, src/bin/ltlfilt.cc,
src/bin/randltl.cc: Include common_sys.hh instead of config.h.
* src/bin/common_output.cc, src/bin/common_output.hh: New file
with the common output code.
* src/bin/Makefile.am: Add them.
* src/bin/genltl.cc, src/bin/ltlfilt.cc: Simplify, using
argp's children parser, and calling output_formula().
