Changes:
- Feedback now syncs against the audio hardware instead of the CPUs timer.
- Query ID3/meta-info from audio streams to set defaults for the Track Name and Artist where available.
- Fixed a crash bug when more than one audio stream was set and they were both missing.
- Added song-specific fretboard customisation. (Fretboard should live in the song's folder with the .chart)

It seemed to me that the number of people reporting the drifting sync over time issue seemed to be increasing.
I could never reproduce this issue myself, so it was terribly difficult for me to isolate the problem, but after some extensive testing, I discovered some strange behaviour with various audio hardware.
It seems that different audio hardware/drivers may operate at slight different frequencies than one would expect. Some sound cards reportedly playing samples at 44100hz did not appear to be holding that exact samplerate when measured against the CPU's high resolution timer.
I've solved this problem by performing all sync relative to the audio hardware's playback cursor. I expect using this technique, nobody should experience any further sync problems over long playback intervals.
If anyone experiences any further issues, please let me know, as all I have is a 'good guess' that this is actually what is causing people problems.

In addition to that important fix, I made a couple of other tweaks.
I've added an option to set song-specific fret-boards. These override the theme fretboards when playing your song.
Also added code to read ID3/vorbis meta-tags to collect default song details, which seemed like a handy feature, and it was a bit of fun to write.
Lastly, I fixed another crash that one user was reporting.
Have fun!