* bin/common_aoutput.hh, bin/common_aoutput.cc,
bin/ltl2tgba.cc, bin/ltldo.cc: Add support for %< and %>.
* tests/core/ltl2tgba.test, tests/core/ltldo.test: Test it.
* NEWS: Mention it.
* bin/common_aoutput.cc, bin/common_aoutput.hh, bin/common_setup.cc:
Implement it.
* NEWS, bin/man/spot-x.x: Document it.
* tests/core/readsave.test: Test it.