Generalize the Consensus Infrastructure (#883)

* Split out Consensus
* Supply ImportQueue through network-service
  - simplify ImportQueue.import_blocks
  - remove Deadlock on import_block
  - Adding Verifier-Trait
  - Implement import_queue provisioning in service; allow cli to import
* Allow to actually customize import queue
* Consensus Gossip: Cache Message hash per Topic

substrate/core/consensus/common/src/lib.rs

@@ -0,0 +1,33 @@
+// Copyright 2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate Consensus Common.
+
+// Substrate Demo is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate Consensus Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate Consensus Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Tracks offline validators.
+#![allow(dead_code)]
+
+#![cfg(feature="rhd")]
+
+extern crate substrate_primitives as primitives;
+
+use primitives::{generic::BlockId, Justification};
+use primitives::traits::{Block, Header};
+
+/// Block import trait.
+pub trait BlockImport<B: Block> {
+	/// Import a block alongside its corresponding justification.
+	fn import_block(&self, block: B, justification: Justification, authorities: &[AuthorityId]) -> bool;
+}
+
+pub mod offline_tracker;