Parameter to allow user to force the sealing mechanism (#918)

* Allow block sealing mechanism to be forced, even when not mining.

* Fix deadlock in dispatch_transaction. Fix tests.

* Horrible workaround for transaction importing.

* Reduce tracing. Cleanups.

* Remove logging.

* Remove broken code inherited from dodgy implementation.

* pre-query tx queue nonce also if any

* remove outside nonce queries

* remove queue nonces

sync/src/chain.rs

@@ -1476,7 +1476,7 @@ mod tests {
 	}
 
 	fn dummy_sync_with_peer(peer_latest_hash: H256) -> ChainSync {
-		let mut sync = ChainSync::new(SyncConfig::default(), Miner::new());
+		let mut sync = ChainSync::new(SyncConfig::default(), Miner::new(false));
 		sync.peers.insert(0,
 		  	PeerInfo {
 				protocol_version: 0,

sync/src/lib.rs

@@ -45,7 +45,7 @@
 //! 	let mut service = NetworkService::start(NetworkConfiguration::new()).unwrap();
 //! 	let dir = env::temp_dir();
 //! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
-//! 	let miner = Miner::new();
+//! 	let miner = Miner::new(false);
 //! 	EthSync::register(&mut service, SyncConfig::default(), client, miner);
 //! }
 //! ```

sync/src/tests/helpers.rs

@@ -93,7 +93,7 @@ impl TestNet {
 		for _ in 0..n {
 			net.peers.push(TestPeer {
 				chain: TestBlockChainClient::new(),
-				sync: ChainSync::new(SyncConfig::default(), Miner::new()),
+				sync: ChainSync::new(SyncConfig::default(), Miner::new(false)),
 				queue: VecDeque::new(),
 			});
 		}