BCX Project Update 023

Hello all BCXers! This is project update 023. BitcoinX 0.16.2 have add the smart contract function, which requires the miners vote to activate. (The voting period is 2016 blocks) 

Currently vvpool and beepool have been updated to the latest version, please update ASAP! 

[Core/dev] Have add the contract inspection rules and reject some non-compliant contract transactions

[Core/dev] Have check the increasing overflow for gasLimit

[Core/dev] Have optimize some execution steps of the contract

[Core/dev] Continue to delve into the latest version of the Ethereum Casper code implementation

[Test] Have add some abnormal test cases of the contract