New sessions, kill consensus module (#2802)

* Draft of new sessions

* Reintroduce tuple impls

* Move staking module to new session API

* More work on staking and grandpa.

* Use iterator to avoid cloning and tuple macro

* Make runtime build again

* Polish the OpaqueKeys devex

* Move consensus logic into system & aura.

* Fix up system module

* Get build mostly going. Stuck at service.rs

* Building again

* Update srml/staking/src/lib.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Refactoring out Consensus module, AuthorityIdOf, &c.

* Refactored out DigestItem::AuthoritiesChanged. Building.

* Remove tentative code

* Remove invalid comment

* Make Seal opaque and introduce nice methods for handling opaque items.

* Start to use proper digest for Aura authorities tracking.

* Fix up grandpa, remove system::Raw/Log

* Refactor Grandpa to use new logging infrastructure.

Also make authorityid/sessionkey static. Switch over to storing
authorities in a straight Vec.

* Building again

* Tidy up some AuthorityIds

* Expunge most of the rest of the AuthorityKey confusion.

Also, de-generify Babe and re-generify Aura.

* Remove cruft

* Untangle last of the `AuthorityId`s.

* Sort out finality_tracker

* Refactor median getting

* Apply suggestions from code review

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

* Session tests works

* Update core/sr-primitives/src/generic/digest.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Session tests works

* Fix for staking from @dvc94ch

* log an error

* fix test runtime build

* Some test fixes

* Staking mock update to new session api.

* Fix build.

* Move OpaqueKeys to primitives.

* Use on_initialize instead of check_rotate_session.

* Update tests to new staking api.

* fixup mock

* Fix bond_extra_and_withdraw_unbonded_works.

* Fix bond_with_little_staked_value_bounded_by_slot_stake.

* Fix bond_with_no_staked_value.

* Fix change_controller_works.

* Fix less_than_needed_candidates_works.

* Fix multi_era_reward_should_work.

* Fix nominating_and_rewards_should_work.

* Fix nominators_also_get_slashed.

* Fix phragmen_large_scale_test.

* Fix phragmen_poc_works.

* Fix phragmen_score_should_be_accurate_on_large_stakes.

* Fix phragmen_should_not_overflow.

* Fix reward_destination_works.

* Fix rewards_should_work.

* Fix sessions_and_eras_should_work.

* Fix slot_stake_is_least_staked_validator.

* Fix too_many_unbond_calls_should_not_work.

* Fix wrong_vote_is_null.

* Fix runtime.

* Fix wasm runtime build.

* Update Cargo.lock

* Fix warnings.

* Fix grandpa tests.

* Fix test-runtime build.

* Fix template node build.

* Fix stuff.

* Update Cargo.lock to fix CI

* Re-add missing AuRa logs

Runtimes are required to know about every digest they receive ― they
panic otherwise.  This re-adds support for AuRa pre-runtime digests.

* Update core/consensus/babe/src/digest.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Kill log trait and all that jazz.

* Refactor staking tests.

* Fix ci runtime wasm check.

* Line length 120.

* Make tests build again

* Remove trailing commas in function declarations

The `extern_functions!` macro doesn’t like them, perhaps due to a bug in
rustc.

* Fix type error

* Fix compilation errors

* Fix a test

* Another couple of fixes

* Fix another test

* More test fixes

* Another test fix

* Bump runtime.

* Wrap long line

* Fix build, remove redundant code.

* Issue to track TODO

* Leave the benchmark code alone.

* Fix missing `std::time::{Instant, Duration}`

* Indentation

* Aura ConsensusLog as enum

substrate/srml/contract/src/lib.rs

@@ -216,7 +216,8 @@ pub struct RawTombstoneContractInfo<H, Hasher>(H, PhantomData<Hasher>);
 
 impl<H, Hasher> RawTombstoneContractInfo<H, Hasher>
 where
-	H: Member + MaybeSerializeDebug + AsRef<[u8]> + AsMut<[u8]> + Copy + Default + rstd::hash::Hash,
+	H: Member + MaybeSerializeDebug + AsRef<[u8]> + AsMut<[u8]> + Copy + Default + rstd::hash::Hash
+		+ Codec,
 	Hasher: Hash<Output=H>,
 {
 	fn new(storage_root: &[u8], code_hash: H) -> Self {

substrate/srml/contract/src/tests.rs

@@ -40,7 +40,7 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use substrate_primitives::storage::well_known_keys;
 use substrate_primitives::Blake2Hasher;
 use system::{self, EventRecord, Phase};
-use {balances, consensus, wabt};
+use {balances, wabt};
 
 mod contract {
 	// Re-export contents of the root. This basically
@@ -72,12 +72,10 @@ impl system::Trait for Test {
 	type BlockNumber = u64;
 	type Hash = H256;
 	type Hashing = BlakeTwo256;
-	type Digest = Digest;
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
 	type Event = MetaEvent;
-	type Log = DigestItem;
 }
 impl balances::Trait for Test {
 	type Balance = u64;
@@ -92,11 +90,6 @@ impl timestamp::Trait for Test {
 	type Moment = u64;
 	type OnTimestampSet = ();
 }
-impl consensus::Trait for Test {
-	type Log = DigestItem;
-	type SessionKey = UintAuthorityId;
-	type InherentOfflineReport = ();
-}
 impl Trait for Test {
 	type Currency = Balances;
 	type Call = Call;
@@ -1002,7 +995,8 @@ const CODE_CHECK_DEFAULT_RENT_ALLOWANCE: &str = r#"
 	)
 )
 "#;
-const HASH_CHECK_DEFAULT_RENT_ALLOWANCE: [u8; 32] = hex!("4f9ec2b94eea522cfff10b77ef4056c631045c00978a457d283950521ecf07b6");
+const HASH_CHECK_DEFAULT_RENT_ALLOWANCE: [u8; 32] =
+	hex!("4f9ec2b94eea522cfff10b77ef4056c631045c00978a457d283950521ecf07b6");
 
 #[test]
 fn default_rent_allowance_on_create() {