`panhuman-2` index based on HPRC release 2

[bede]

• Build for w=15,17,19,21
• Evaluate performance:
  • With varying w
  • With panhuman-1
• Publish

[pmenzel]

just saw this https://github.com/lh3/OpenHGL, maybe worth adding as an extra index, too?

[bede]

Thanks @pmenzel, had seen this but need to look into it.