Cuetools.Converter.exe: support for --decoder-option parameter.

Implemented "Stream" option in BDLPCM Reader to make it possible to select
the right stream in m2ts file.

CUETools.Codecs/SilenceGenerator.cs

@@ -6,6 +6,8 @@
         private AudioPCMConfig pcm;
         private int _sampleVal;
 
+        public AudioDecoderSettings Settings { get { return null; } }
+
         public long Length
         {
             get { return _sampleCount; }