* {core,srml}/authority-discovery: Move generic to specific session keys

* {srml,core}/authority-discovery: Verify signature outside of runtime

Given that the `core/authority-discovery` uses concrete authority
identifiers and signatures, one can verify a signature with the
authority discovery within `core`. Given the above, the `verify` runtime
api is obsolete and thus removed.

* *: Add authority discovery to the set of session keys

* *: Sign authority discovery DHT payload with keystore instead of runtime

Instead of calling a runtime function to sign a dht payload, which then
invokes the keystore, pass the keystore to the authority discovery
module and use it directly.

* core/authority-discovery: Give libp2p Kademlia time to start up

* core/authority-discovery: Move authorities priority group name to const

* node/runtime/src/lib.rs: Bump runtime spec version

* *: Fix lints and node/testing test failures

* *: Fix formatting

* core/authority-discovery: Box dht event channel in unit tests

* node/cli/src/service.rs: Fix future import

* node/cli/src/service.rs: Replace unwrap by expect with proof

* node/cli/src/chain_spec: Remove TODO for testnet key generation

* core/authority-discovery/src/lib: Remove scale encoding TODOs

* srml/authority-discovery: Make comment a doc comment

* core/authority-discovery: Remove unused StreamExt import

* node/runtime: Bump impl version to debug CI

* Test ci.

* Change the line width to 100.

* Revert "Change the line width to 100."

This reverts commit edff1f85.

* Fix a check for polkadot to work on forked repos.

* Revert "node/runtime: Bump impl version to debug CI"

This reverts commit 1a90903b.

* Revert "Test ci."

This reverts commit a2c9df57.

* Cargo.lock: Fix wrong lock file merge

* srml/authority-discovery: Keep track of new validator set not upcoming

* core/authority-discovery: Document key retrieval functions

* Wasm diagnostics

* Pass the error

* Make errno optional

* Cargo.lock

* Log the error

* make linked_map generic functions better

* implement translation of linked map

* proc-macro for linked map updated

* test linked map migration

* account for instances

* address grumbles

* cut map short if migration fails

* drafting a proof extraction at the hashdb level (to include everything
for the 'call' proof case).

* use full proof by default (replace previous proof recorder).

* fix warnings.

* Cache value not found in proof recorder.

* Remove need or internal backend struct.

* fix type.

* doc

* randomized tests

* destroy clones

* remove commented

* fixes

* add finalization fork

* Initial version that works with proper tests.

* get rid of todos and grumbles and such.

* Cleanup and fix line-width

* fix test runtime test

This lets us drop a couple old dependencies, which is nice.

* Work around finalization woes

* Fixed check_block

* Added a test

* update tiny-keccak

* fix

* Update Cargo.toml

* update Cargo.lock

* remove keccak-hasher