This is an implementation of Krishnan's ISAAC'94 paper to convert
deterministic Rabin automata into DBA when possible.
* src/dstarparse/dra2dba.cc: New file.
* src/dstarparse/dstar2tgba.cc: New file.
* src/dstarparse/Makefile.am: Add them.
* src/dstarparse/nra2nba.cc (nra_to_nba): Adjust so
that dra_to_dba() can call it using a masked automaton.
* src/dstarparse/public.hh (dra_to_dba, dstar_to_tgba): Declare.
* src/tgbatest/ltl2tgba.cc: Add an -XDD option.
* src/tgbatest/dstar.test: More tests.