Light friendly storage tracking: changes trie + extending over ranges (#628)

* changes_trie

* changs_trie: continue

* changes_trie: adding tests

* fixed TODO

* removed obsolete ExtrinsicChanges

* encodable ChangesTrieConfiguration

* removed polkadot fle

* fixed grumbles

* ext_storage_changes_root returns u32

* moved changes trie root to digest

* removed commented code

* read storage values from native code

* fixed grumbles

* fixed grumbles

* missing comma

substrate/core/sr-primitives/src/testing.rs

@@ -20,16 +20,20 @@ use serde::{Serialize, de::DeserializeOwned};
 use std::fmt::Debug;
 use codec::Codec;
 use traits::{self, Checkable, Applyable, BlakeTwo256};
+use generic::DigestItem as GenDigestItem;
 
 pub use substrate_primitives::H256;
 
+pub type DigestItem = GenDigestItem<H256, u64>;
+
 #[derive(Default, PartialEq, Eq, Clone, Serialize, Deserialize, Debug, Encode, Decode)]
 pub struct Digest {
-	pub logs: Vec<u64>,
+	pub logs: Vec<DigestItem>,
 }
 
 impl traits::Digest for Digest {
-	type Item = u64;
+	type Hash = H256;
+	type Item = DigestItem;
 
 	fn logs(&self) -> &[Self::Item] {
 		&self.logs
@@ -40,14 +44,6 @@ impl traits::Digest for Digest {
 	}
 }
 
-impl traits::DigestItem for () {
-	type AuthorityId = ();
-}
-
-impl traits::DigestItem for u64 {
-	type AuthorityId = ();
-}
-
 #[derive(PartialEq, Eq, Clone, Serialize, Deserialize, Debug, Encode, Decode)]
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
@@ -88,7 +84,11 @@ impl traits::Header for Header {
 		digest: Self::Digest
 	) -> Self {
 		Header {
-			number, extrinsics_root: extrinsics_root, state_root, parent_hash, digest
+			number,
+			extrinsics_root: extrinsics_root,
+			state_root,
+			parent_hash,
+			digest
 		}
 	}
 }