This implements 1b & 1c of EIP150 by adding a new GasTable which must be
returned from the RuleSet config method. This table is used to determine
the gas prices for the current epoch.
Please note that when the CreateBySuicide gas price is set it is assumed
that we're in the new epoch phase.
In addition this PR will serve as temporary basis while refactorisation
in being done in the EVM64 PR, which will substentially overhaul the gas
price code.
Two new tests are skipped because they're buggy. Making some newer
random state tests work required implementing the 'compressed return
value encoding'.
* 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
