Important updates:
- accurate QSound emulation (thanks to ctr)
- slightly improved emulation of YMF278B, YMF271, SAA1099 and C352
- added Nuked OPN2 sound core (cycle-accurate YM2612 emulation, thanks to Nuke.YKT)
- in_vgm: fixed some bugs
- in_vgm: made "Tag fallback" option work
- in_vgm: fixed display of outdated tag information