Updated SDL_mixer with new versions of audio libraries, including SMPEG 2.0, and fixed Visual C++ build.

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rename : VisualC/SDL_mixer.sln => VisualC/SDL_mixer_VS2008.sln
rename : VisualC/SDL_mixer.vcproj => VisualC/SDL_mixer_VS2008.vcproj
rename : VisualC/native_midi/native_midi.vcproj => VisualC/native_midi/native_midi_VS2008.vcproj
rename : VisualC/playmus/playmus.vcproj => VisualC/playmus/playmus_VS2008.vcproj
rename : VisualC/playwave/playwave.vcproj => VisualC/playwave/playwave_VS2008.vcproj
rename : VisualC/timidity/timidity.vcproj => VisualC/timidity/timidity_VS2008.vcproj
rename : libmikmod-3.1.12.zip => external/libmikmod-3.1.12.zip
Extracted source so mobile builds work out of the box
Updated Info.plist for new version

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rename : Xcode/Info-Framework__Upgraded_.plist => Xcode/Info-Framework.plist
Updated Mac OS X frameworks, and re-added MP3 support to SDL_mixer
SDL_LoadMUS_RW() now takes an argument telling whether or not the data source should be freed when done.
Fixes crashes cleaning up the data source for music when loading fails.
Updated Android build, including MOD, MP3 and OGG music support.
Updated iOS project to include OGG support directly
Fixed double-free if MOD music playback fails
Switched Mac OS X framework to use weak linking on external libraries.
This allows someone to just remove the smpeg2.framework if they don't want MP3 support, for example.
The weak import attribute is necessary to prevent the optimizer from eliminating the symbol NULL check.