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/finality-tracker/src/lib.rs

@@ -202,7 +202,7 @@ impl<T: Trait> Module<T> {
 			let delay = latency + (window_size / two);
 			// median may be at most n - delay
 			if median + delay <= now {
-				T::OnFinalizationStalled::on_stalled(window_size - T::BlockNumber::one());
+				T::OnFinalizationStalled::on_stalled(window_size - T::BlockNumber::one(), median);
 			}
 		}
 	}
@@ -212,20 +212,20 @@ impl<T: Trait> Module<T> {
 pub trait OnFinalizationStalled<N> {
 	/// The parameter here is how many more blocks to wait before applying
 	/// changes triggered by finality stalling.
-	fn on_stalled(further_wait: N);
+	fn on_stalled(further_wait: N, median: N);
 }
 
 macro_rules! impl_on_stalled {
 	() => (
 		impl<N> OnFinalizationStalled<N> for () {
-			fn on_stalled(_: N) {}
+			fn on_stalled(_: N, _: N) {}
 		}
 	);
 
 	( $($t:ident)* ) => {
 		impl<NUM: Clone, $($t: OnFinalizationStalled<NUM>),*> OnFinalizationStalled<NUM> for ($($t,)*) {
-			fn on_stalled(further_wait: NUM) {
-				$($t::on_stalled(further_wait.clone());)*
+			fn on_stalled(further_wait: NUM, median: NUM) {
+				$($t::on_stalled(further_wait.clone(), median.clone());)*
 			}
 		}
 	}
@@ -263,7 +263,7 @@ mod tests {
 	use substrate_primitives::H256;
 	use primitives::BuildStorage;
 	use primitives::traits::{BlakeTwo256, IdentityLookup, OnFinalize, Header as HeaderT};
-	use primitives::testing::{Digest, DigestItem, Header};
+	use primitives::testing::Header;
 	use srml_support::impl_outer_origin;
 	use srml_system as system;
 	use lazy_static::lazy_static;
@@ -290,12 +290,10 @@ mod tests {
 				type BlockNumber = u64;
 				type Hash = H256;
 				type Hashing = BlakeTwo256;
-				type Digest = Digest;
 				type AccountId = u64;
 				type Lookup = IdentityLookup<u64>;
 				type Header = Header;
 				type Event = ();
-				type Log = DigestItem;
 			}
 
 			type System = system::Module<Test>;
@@ -306,7 +304,7 @@ mod tests {
 
 			pub struct StallTracker;
 			impl OnFinalizationStalled<u64> for StallTracker {
-				fn on_stalled(further_wait: u64) {
+				fn on_stalled(further_wait: u64, _median: u64) {
 					let now = System::block_number();
 					NOTIFICATIONS.lock().push(StallEvent { at: now, further_wait });
 				}