Audio extraction from DVD-Audio discs

Audio extraction has been (partly) restored to working status, using the following options:
--aob-extract (AOB file or disc/directory containing an AOB file) : to extract to raw PCM files (headerless WAVs) or to extract MLP files from discs
--aob2wav (AOB file or disc/directory containing an AOB file) : to extract to WAV. This is only for PCM discs, for MLP discs use --aob-extract.
Option -x (--extract) is broken and will be fixed.