Update SIGNEXTEND definition and tests
Update SIGNEXTEND definition and tests

Conflicts:
	libevm/VM.h
	test/vmBitwiseLogicOperationTestFiller.json

ethers/solidity,gluk256/solidity,LianaHus/solidity,vaporry/solidity,douglas-larocca/solidity,arkpar/solidity,ruchevits/solidity,shahankhatch/solidity,ruchevits/solidity,debris/solidity,ruchevits/solidity,chriseth/solidity-doc-test,chriseth/solidity,ruchevits/solidity