[beta] Byzantium updates (#6529)

* fix modexp bug: return 0 if base=0 (#6424)

* Running state test using parity-evm (#6355)

* Initial version of state tests.

* Refactor state to support tracing.

* Unify TransactResult.

* Add test.

* Byzantium updates

ethcore/src/client/test_client.rs

@@ -595,6 +595,7 @@ impl BlockChainClient for TestBlockChainClient {
 		if *hash > H256::from("f000000000000000000000000000000000000000000000000000000000000000") {
 			let receipt = BlockReceipts::new(vec![Receipt::new(
 				Some(H256::zero()),
+				None,
 				U256::zero(),
 				vec![])]);
 			let mut rlp = RlpStream::new();