Open Items PoS transition

[scravy]

• Restore functional tests that relied on BIP 22 and BIP 23: https://github.com/dtr-org/unit-e/issues/280 (important in general and to merge with upstream 0.17)
• [ ] Adapt generate RPC call (important to have functional tests working with new PoS setting, 0.1)
  • be aware: generate is being deprecated in bitcoin and generatetoaddress should be used
  • currently generate mines blocks on lowest difficulty, new generate requires a wallet to sign transactions/blocks
  • preliminary work for this has been done in: https://github.com/dtr-org/unit-e/pull/613
  • is being done in #738
• [ ] Make sure BIP9 works/works again (correct version has to be set in staking::BlockBuilder, right now it just sets something (dunno, 1, or 2).
  • Related: https://github.com/dtr-org/unit-e/issues/472
  • We do not want to have the current softforks enabled as softforks as we do support them by default, but we do want to support BIP9 for future compatibility with bitcoin (probably, see discussion)
  • BIP9: https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki
• [ ] Duplicate Stake Attack Protection: (1.0)
  • https://github.com/dtr-org/unit-e/issues/416
  • we do have some preparations for it in StakeValidator
  • in particl they have an nFlags member on CBlock which is used to check this and propagate it do different parts of the core software
• [ ] Store or recompute stake_amount / chain_stake in CBlockIndex or differently (1.0)
  • https://github.com/dtr-org/unit-e/issues/534
  • bitcoin uses nChainWork
  • is supposed to become chain_stake
  • interacts with ABC (ActivateBestChain)
• Store or recompute stake_modifier in CBlockIndex or differently (1.0)
  • https://github.com/dtr-org/unit-e/issues/535

[Ruteri]

Restore functional tests that relied on BIP 22 and BIP 23: #280 (important in general and to merge with upstream 0.17)

Done.

Related issues: https://github.com/dtr-org/unit-e/issues/280 and https://github.com/dtr-org/unit-e/issues/283.