List node pointers in MilesAudioManager

```cpp
std::list<PlayingAudio *> m_playingSounds;
std::list<PlayingAudio *> m_playing3DSounds;
std::list<PlayingAudio *> m_playingStreams;
std::list<PlayingAudio *> m_fadingAudio;
```

These guys can perhaps be simplified to

```
std::list<PlayingAudio> m_playingSounds;
std::list<PlayingAudio> m_playing3DSounds;
std::list<PlayingAudio> m_playingStreams;
std::list<PlayingAudio> m_fadingAudio;