Consensus Engines Implementation: Aura (#911)

* Generalize BlockImport

 - move ImportBlock, BlockOrigin, ImportResult into shared sr-primitives
 - let Consensus provide  and  traits again
 - update consensus traits to latest development
 - implement traits on client::Client, test_client::TestClient
 - update RHD to use the new import_block API

* Move ImportBlock into consensus-common
* Send import notification in aura tests
* Integrating aura into service
* Make Signatures more generic
* Aura Block Production with the given key
* run aura on the thread pool
* start at exact step start in aura
* Add needed wasm blob, in leiu of better solutions.
* Make API ids consistent with traits and bring upstream for sharing.
* Add decrease_free_balance to Balances module
* Encode `Metadata` once instead of two times
* Bitops include xor
* Upgrade key module.
* Default pages to somewhat bigger.
* Introduce upgrade key into node
* Add `Created` event

substrate/core/sr-primitives/src/generic/digest.rs

@@ -21,6 +21,8 @@ use rstd::prelude::*;
 use codec::{Decode, Encode, Codec, Input};
 use traits::{self, Member, DigestItem as DigestItemT};
 
+use substrate_primitives::hash::H512 as Signature;
+
 #[derive(PartialEq, Eq, Clone, Encode, Decode)]
 #[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
 pub struct Digest<Item> {
@@ -46,6 +48,10 @@ impl<Item> traits::Digest for Digest<Item> where
 	fn push(&mut self, item: Self::Item) {
 		self.logs.push(item);
 	}
+
+	fn pop(&mut self) -> Option<Self::Item> {
+		self.logs.pop()
+	}
 }
 
 /// Digest item that is able to encode/decode 'system' digest items and
@@ -60,10 +66,13 @@ pub enum DigestItem<Hash, AuthorityId> {
 	/// block. It is created for every block iff runtime supports changes
 	/// trie creation.
 	ChangesTrieRoot(Hash),
+	/// Put a Seal on it
+	Seal(u64, Signature),
 	/// Any 'non-system' digest item, opaque to the native code.
 	Other(Vec<u8>),
 }
 
+
 /// A 'referencing view' for digest item. Does not own its contents. Used by
 /// final runtime implementations for encoding/decoding its log items.
 #[derive(PartialEq, Eq, Clone)]
@@ -73,6 +82,9 @@ pub enum DigestItemRef<'a, Hash: 'a, AuthorityId: 'a> {
 	AuthoritiesChange(&'a [AuthorityId]),
 	/// Reference to `DigestItem::ChangesTrieRoot`.
 	ChangesTrieRoot(&'a Hash),
+	/// A sealed signature for testing
+	Seal(&'a u64, &'a Signature),
+	/// Any 'non-system' digest item, opaque to the native code.
 	/// Reference to `DigestItem::Other`.
 	Other(&'a Vec<u8>),
 }
@@ -87,6 +99,7 @@ enum DigestItemType {
 	Other = 0,
 	AuthoritiesChange,
 	ChangesTrieRoot,
+	Seal,
 }
 
 impl<Hash, AuthorityId> DigestItem<Hash, AuthorityId> {
@@ -103,6 +116,7 @@ impl<Hash, AuthorityId> DigestItem<Hash, AuthorityId> {
 		match *self {
 			DigestItem::AuthoritiesChange(ref v) => DigestItemRef::AuthoritiesChange(v),
 			DigestItem::ChangesTrieRoot(ref v) => DigestItemRef::ChangesTrieRoot(v),
+			DigestItem::Seal(ref v, ref s) => DigestItemRef::Seal(v, s),
 			DigestItem::Other(ref v) => DigestItemRef::Other(v),
 		}
 	}
@@ -137,6 +151,10 @@ impl<Hash: Decode, AuthorityId: Decode> Decode for DigestItem<Hash, AuthorityId>
 			DigestItemType::ChangesTrieRoot => Some(DigestItem::ChangesTrieRoot(
 				Decode::decode(input)?,
 			)),
+			DigestItemType::Seal => {
+				let vals: (u64, Signature) = Decode::decode(input)?;
+				Some(DigestItem::Seal(vals.0, vals.1))
+			},
 			DigestItemType::Other => Some(DigestItem::Other(
 				Decode::decode(input)?,
 			)),
@@ -173,6 +191,10 @@ impl<'a, Hash: Encode, AuthorityId: Encode> Encode for DigestItemRef<'a, Hash, A
 				DigestItemType::ChangesTrieRoot.encode_to(&mut v);
 				changes_trie_root.encode_to(&mut v);
 			},
+			DigestItemRef::Seal(val, sig) => {
+				DigestItemType::Seal.encode_to(&mut v);
+				(val, sig).encode_to(&mut v);
+			},
 			DigestItemRef::Other(val) => {
 				DigestItemType::Other.encode_to(&mut v);
 				val.encode_to(&mut v);

substrate/core/sr-primitives/src/generic/header.rs

@@ -137,6 +137,7 @@ impl<Number, Hash, DigestItem> traits::Header for Header<Number, Hash, DigestIte
 	fn set_parent_hash(&mut self, hash: Self::Hash) { self.parent_hash = hash }
 
 	fn digest(&self) -> &Self::Digest { &self.digest }
+	fn digest_mut(&mut self) -> &mut Self::Digest { &mut self.digest }
 	fn set_digest(&mut self, digest: Self::Digest) { self.digest = digest }
 
 	fn new(