separate trie from util and make its dependencies into libs:

* bytes
* hashdb
* memorydb
* nibbleslice
* nibblevec

ethcore/src/verification/queue/kind.rs

@@ -77,7 +77,7 @@ pub mod blocks {
 	use heapsize::HeapSizeOf;
 	use bigint::prelude::U256;
 	use bigint::hash::H256;
-	use util::Bytes;
+	use bytes::Bytes;
 
 	/// A mode for verifying blocks.
 	pub struct Blocks;

ethcore/src/verification/verification.rs

@@ -26,8 +26,8 @@ use hash::keccak;
 use triehash::ordered_trie_root;
 use heapsize::HeapSizeOf;
 use bigint::hash::H256;
-use util::*;
 use unexpected::{Mismatch, OutOfBounds};
+use bytes::Bytes;
 use engines::Engine;
 use error::{BlockError, Error};
 use blockchain::*;
@@ -276,7 +276,7 @@ mod tests {
 	use bigint::hash::{H256, H2048};
 	use triehash::ordered_trie_root;
 	use unexpected::{Mismatch, OutOfBounds};
-	use util::*;
+	use bytes::Bytes;
 	use ethkey::{Random, Generator};
 	use header::*;
 	use verification::*;