* change gas cost for contract creating txs
* invalidate signature with s value greater than secp256k1 N / 2
* OOG contract creation if not enough gas to store code
* new difficulty adjustment algorithm
* new DELEGATECALL op code

Conflicts:
	core/vm/environment.go
	crypto/crypto.go
	crypto/secp256k1/secp256.go
	eth/api.go