* Restore the homestead flag which was incorrectly removed previously when byzantium was enabled.
Impact of having it disabled is that a number of homestead features are not enabled; for example, if child contract creation runs out of gas then contract address is returned instead of error “contract creation code storage out of gas”.
* Added the Constantinople flag and upgraded to work with quorum v2.2.4.
Also restored the homestead flag that was incorrectly removed previously when byzantium was enabled.
* Fixed TransactionSizeLimit, added IsQuorum and changed flags to start at block zero.