Signer transaction replay enforcement

[obycode]

This is the other side of the miner task defined in issue #4313. The signers should enforce this transaction replay behavior by refusing to sign a block that does not replay the transactions in the same order after a Bitcoin reorg.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[obycode]

This cannot be closed yet.