* bin/common_post.cc, bin/randaut.cc: Implement -b/--buchi.
Also add --sba as alias for -B, and --gba as alias for --tgba.
* NEWS: Document those changes.
* doc/org/ltl2tgba.org, doc/org/oaut.org: Adjust documentation.
* tests/core/ltl2tgba2.test, tests/core/ltlcross2.test,
tests/core/randaut.test: Add more tests.
* tests/core/sbacc.test: --sbacc cannot be abbreviated as --sba
anymore.