Improvements to audout (#58)

* Some audout refactoring and improvements

* More audio improvements

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

Ryujinx.Core/Settings/SystemSettings.cs

@@ -0,0 +1,7 @@
+namespace Ryujinx.Core.Settings
+{
+    public class SystemSettings
+    {
+        public ColorSet ThemeColor;
+    }
+}