#492 bugfix, for SPDIF audio ouput of AC3 and DTS sound on Windows

#492 bugfix, for SPDIF audio ouput of AC3 and DTS sound on Windows
(but its still critical because it happens - aout_OutputNextBuffer(...) has no buffers
available - sometime the output doesn't know until some ms before the last block
has finished to play! so each little disturbtion of the CPU or load change
leads to studdering/hickups)

#897 enhancement: give the use the option to choose its prefered audio device,
instead of useing Windows default