separate trie from util and make its dependencies into libs:

* bytes
* hashdb
* memorydb
* nibbleslice
* nibblevec

ethcore/src/engines/validator_set/contract.rs

@@ -21,6 +21,7 @@ use std::sync::Weak;
 use bigint::hash::H256;
 use parking_lot::RwLock;
 use util::*;
+use bytes::Bytes;
 
 use futures::Future;
 use native_contracts::ValidatorReport as Provider;
@@ -139,6 +140,7 @@ mod tests {
 	use hash::keccak;
 	use bigint::hash::H520;
 	use util::*;
+	use bytes::ToPretty;
 	use rlp::encode;
 	use spec::Spec;
 	use header::Header;

ethcore/src/engines/validator_set/mod.rs

@@ -26,7 +26,8 @@ mod multi;
 use std::sync::Weak;
 use ids::BlockId;
 use bigint::hash::H256;
-use util::{Bytes, Address};
+use util::Address;
+use bytes::Bytes;
 use ethjson::spec::ValidatorSet as ValidatorSpec;
 use client::EngineClient;
 use header::{Header, BlockNumber};

ethcore/src/engines/validator_set/multi.rs

@@ -21,7 +21,8 @@ use std::sync::Weak;
 use engines::{Call, Engine};
 use bigint::hash::H256;
 use parking_lot::RwLock;
-use util::{Bytes, Address};
+use util::Address;
+use bytes::Bytes;
 use ids::BlockId;
 use header::{BlockNumber, Header};
 use client::EngineClient;

ethcore/src/engines/validator_set/safe_contract.rs

@@ -26,6 +26,7 @@ use bigint::hash::{H160, H256};
 use parking_lot::{Mutex, RwLock};
 
 use util::*;
+use bytes::Bytes;
 use util::cache::MemoryLruCache;
 use unexpected::Mismatch;
 use rlp::{UntrustedRlp, RlpStream};

ethcore/src/engines/validator_set/test.rs

@@ -21,7 +21,8 @@ use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering as AtomicOrdering};
 use heapsize::HeapSizeOf;
 use bigint::hash::H256;
-use util::{Bytes, Address};
+use util::Address;
+use bytes::Bytes;
 
 use engines::{Call, Engine};
 use header::{Header, BlockNumber};