Back to CPU mining! Soon... what!!!? 
Currently testing HF5, where we switch from ethash to argon2id
This is to prevent ASIC takeover, E3, etc.
🔌 HF5: Argonated * Switch POW algorithm to argon2id
* Better testnet (just run with -testnet flag to try the new algo out)
If this PR works as expected, and is merged, HF5 is activated on mainnet on block 22800.
Things to consider while testing:
* Difficulty, rate of change
* Average time
* Lucky blocks frequency
* Choice of argon2d package
* This is super alpha test version. Log output is slightly more verbose than normal.
* Syncing from scratch
* Export chain Import chain