DAO hard-fork (#1483)

* Minor additions to allow resetting of code.

* Add test.

* Provisional DAO hard-fork proposal.

* Change to reflect latest HF spec.

* Include extradata restrictions and overrides.

* Introduce new tests.

* Update tests to new spec format.

* Allow JSON chain spec fields to be optional.

* Remove superfluous definitions. Fix overflow risk.

* Fix build.

* Add missing file.

* Remove old flag.

* Update to latest address set.

* Update tests and test spec to latest.

Change the mining default to release only on own transactions.

json/src/spec/engine.rs

@@ -53,7 +53,10 @@ mod tests {
 					"durationLimit": "0x0d",
 					"blockReward": "0x4563918244F40000",
 					"registrar" : "0xc6d9d2cd449a754c494264e1809c50e34d64562b",
-					"frontierCompatibilityModeLimit" : "0x"
+					"frontierCompatibilityModeLimit" : "0x",
+					"daoHardforkTransition": "0xffffffffffffffff",
+					"daoHardforkBeneficiary": "0x0000000000000000000000000000000000000000",
+					"daoHardforkAccounts": []
 				}
 			}
 		}"#;