Expunge error-chain (feat. tomaka) (#2662)

* Remove error_chain

* Expunge error-chain from rpc and service.

* Expunge from transaction pool.

* Expunge from node/cli

* Expunge from keystore.

* Remove some boilerplate.

* Fix remaining stuff.

* Improve on deprecation message.

* Fix issues.

* Fix trnsaction pool tests.

* Fix the rest.

* Fix borked merge.

* Update lock

substrate/core/client/db/src/cache/list_cache.rs

@@ -45,7 +45,7 @@ use log::warn;
 
 use client::error::{Error as ClientError, Result as ClientResult};
 use runtime_primitives::traits::{
-	Block as BlockT, NumberFor, Zero, Bounded, SaturatedConversion, CheckedSub
+	Block as BlockT, NumberFor, Zero, Bounded, CheckedSub
 };
 
 use crate::cache::{CacheItemT, ComplexBlockId, EntryType};

substrate/core/client/db/src/lib.rs

@@ -48,7 +48,7 @@ use primitives::storage::well_known_keys;
 use runtime_primitives::{generic::BlockId, Justification, StorageOverlay, ChildrenStorageOverlay};
 use runtime_primitives::traits::{
 	Block as BlockT, Header as HeaderT, NumberFor, Zero, One, Digest, DigestItem,
-	SaturatedConversion, UniqueSaturatedFrom, UniqueSaturatedInto
+	SaturatedConversion,
 };
 use runtime_primitives::BuildStorage;
 use state_machine::backend::Backend as StateBackend;

substrate/core/client/db/src/utils.rs

@@ -31,7 +31,7 @@ use trie::DBValue;
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::traits::{
 	Block as BlockT, Header as HeaderT, Zero, UniqueSaturatedFrom,
-	UniqueSaturatedInto, SaturatedConversion, CheckedConversion
+	UniqueSaturatedInto, CheckedConversion
 };
 use crate::DatabaseSettings;