Fixed mp3 playback on linux and added support for mono mp3s

src/modules/sound/lullaby/Mpg123Decoder.h

@@ -1,14 +1,14 @@
 /**
 * Copyright (c) 2006-2010 LOVE Development Team
-* 
+*
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
-* 
+*
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
-* 
+*
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
@@ -48,11 +48,13 @@ namespace lullaby
 		int data_offset;
 		int data_size;
 
+		int channels;
+
 	public:
 
 		Mpg123Decoder(Data * data, const std::string & ext, int bufferSize, int sampleRate);
 		virtual ~Mpg123Decoder();
-		
+
 		static bool accepts(const std::string & ext);
 		static void quit();