Improvements to audout (#58)

* Some audout refactoring and improvements

* More audio improvements

* Change ReadAsciiString to use long for the Size, avoids some casting

Ryujinx.Audio/IAalOutput.cs

@@ -0,0 +1,18 @@
+namespace Ryujinx.Audio
+{
+    public interface IAalOutput
+    {
+        int OpenTrack(int SampleRate, int Channels, out AudioFormat Format);
+        void CloseTrack(int Track);
+
+        void AppendBuffer(int Track, long Tag, byte[] Buffer);        
+        bool ContainsBuffer(int Track, long Tag);
+
+        long[] GetReleasedBuffers(int Track);
+
+        void Start(int Track);
+        void Stop(int Track);
+
+        PlaybackState GetState(int Track);
+    }
+}