A unit test for the ITA_AUDIO file formats
Catch an exception, so that the unit test for the termination of octave
runs on Windows as well.
Improve the unit test for the behavior in case of a missing library.
 - Pass an integer flag instead of a function to a multiprocessing.Process
   to increase the chances, that this test runs on Windows one day.
 - Check also for the file formats that rely on oct2py.