bin: plug several memory leaks

* src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc: Destroy the translated
formulas.
* src/bin/ltlcheck.cc, src/bin/ltlfilt.cc: Free the unicity table on
exit.

src/bin/ltl2tgta.cc

@@ -229,6 +229,7 @@ namespace
 	}
 
       delete aut;
+      f->destroy();
       flush_cout();
       return 0;
     }