separate trie from util and make its dependencies into libs:

* bytes
* hashdb
* memorydb
* nibbleslice
* nibblevec

ethcore/src/views/block.rs

@@ -18,7 +18,7 @@
 
 use hash::keccak;
 use bigint::hash::H256;
-use util::*;
+use bytes::Bytes;
 use header::*;
 use transaction::*;
 use super::{TransactionView, HeaderView};

ethcore/src/views/body.rs

@@ -18,7 +18,7 @@
 
 use hash::keccak;
 use bigint::hash::H256;
-use util::*;
+use bytes::Bytes;
 use header::*;
 use transaction::*;
 use super::{TransactionView, HeaderView};

ethcore/src/views/header.rs

@@ -19,7 +19,8 @@
 use hash::keccak;
 use bigint::prelude::U256;
 use bigint::hash::{H256, H2048};
-use util::{Bytes, Address};
+use util::Address;
+use bytes::Bytes;
 use rlp::Rlp;
 use header::BlockNumber;
 

ethcore/src/views/transaction.rs

@@ -17,7 +17,7 @@
 //! View onto transaction rlp
 use bigint::prelude::U256;
 use bigint::hash::H256;
-use util::Bytes;
+use bytes::Bytes;
 use hash::keccak;
 use rlp::Rlp;