Constantinople Implementation Progress

[jwasinger]

The following EIPs need to be implemented for EthereumJSVM to be compatible with the upcoming Constantinople hardfork:

• EIP 145 bitwise: Implement bitwise shifting #251
• EIP 1014 CREATE2: work in progress
• EIP 1052 EXTCODEHASH: work in progress
• EIP 1283 SSTORE net metering without dirty maps (replaces EIP-1087): not started yet
• EIP 1234 Constantinople difficulty bomb delay and block reward adjustment (difficulty part in ethereumjs-block, see Byzantium PR for reference)

[holgerd77]

Updated this with the latest changes from the progress tracker (EIP-1087 -> EIP-1283, added EIP-1234 with reference to ethereumjs-block library).

[holgerd77]

Will close in favor of project https://github.com/ethereumjs/ethereumjs-vm/projects/1 and issues for the separate EIPs, then we have more fine-grained EIP implementation discussions.