Backport core PRs to stable (#7892)

* update back-references more aggressively after answering from cache (#7578)

* Flush keyfiles. Resolves #7632 (#7868)

* Fix wallet import (#7873)

* rpc: generate new account id for imported wallets

* ethstore: handle duplicate wallet filenames

* ethstore: simplify deduplication of wallet file names

* ethstore: do not dedup wallet filenames on update

* ethstore: fix minor grumbles

* parity-version pr reopen (#7136)

* parity-version module split from util

removed unused util deps and features

trigger buildbot again

only kvdb links rocksdb

snappy linker issues

* rm snappy

* fixed old version imports

* Move updater metadata to Cargo.toml of parity-version. (#7832)

* Update version.

* Bump parity version.

* Fix version.

* Fix compilation.

ethcore/src/engines/basic_authority.rs

@@ -29,7 +29,6 @@ use ethjson;
 use header::Header;
 use client::EngineClient;
 use machine::{AuxiliaryData, Call, EthereumMachine};
-use semantic_version::SemanticVersion;
 use super::signer::EngineSigner;
 use super::validator_set::{ValidatorSet, SimpleList, new_validator_set};
 
@@ -95,7 +94,6 @@ impl BasicAuthority {
 
 impl Engine<EthereumMachine> for BasicAuthority {
 	fn name(&self) -> &str { "BasicAuthority" }
-	fn version(&self) -> SemanticVersion { SemanticVersion::new(1, 0, 0) }
 
 	fn machine(&self) -> &EthereumMachine { &self.machine }
 
@@ -218,7 +216,6 @@ mod tests {
 	fn has_valid_metadata() {
 		let engine = new_test_authority().engine;
 		assert!(!engine.name().is_empty());
-		assert!(engine.version().major >= 1);
 	}
 
 	#[test]