[WIP] tra2tba: Implement transformation of TRA to TBA acceptance condition.
- python/spot/impl.i: Add bindings for tra2tba.
- spot/twaalgos/Makefile.am: Record tra2tba.cc, tra2tba.hh.
- spot/twaalgos/tra2tba.cc: Implement transformation of TRA to TBA.
- spot/twaalgos/tra2tba.hh: Introduce declaration of tra_to_tba.
- tests/Makefile.am: Record tra2tba tests.
- tests/core/tra2tba.cc: Add driver for tests.
- tests/core/tra2tba.test: Add tests of tra2tba transformation.