Proposed changes for Hard Fork

[l0k18]

• Adding Proof of Work verifiers and PoW modes for pod:
  • Equihash (GPU and ASIC mineable)
  • Cryptonote 6 and 7 (latter only GPU mineable)
  • Cuckoo Cycle (CPU and GPU mineable, no ASIC known, experimental ? )
• Change to similar difficulty adjustment as Monero:
  • 288 blocks back (per algorithm, so up to 5 days with all algos running)
  • blocks are sorted
  • top 22 and bottom 22 block times are removed
  • old difficulty * average time * actual time (or max 4 and 6 minutes limited) / target time = new difficulty
• Change reward calculation to exponential decay following the same curve but block-by-block