Hardfork Meta EIP-1679: Istanbul discussion

[fulldecent]

I have reviewed this EIP and all its dependencies. My complete list of outstanding review comments follows:

• https://github.com/ethereum/EIPs/issues/152#issuecomment-560926710
• Opcode repricing
• EIP-2028: Transaction data gas cost reduction
• https://github.com/sorpaas/EIPs/issues/1#issuecomment-560941990