ANMP 6
- libsndfile: speedup reading float PCM files
- fix blocking UI when adding files to playlist
- improve usability of channel muting dialog
- ability to build against libc++
- add SongInspector GUI
- avoid overlapping notes from killing each other
- make fluidsynth's volume response fit to N64's software synth
- implement an IIR lowpass filter compatible to Rareware's N64 games (CBFD, JFG)