Refactor sr_primitives. (#3214)

* refactor sr_primitives.

* Fix try build error.

* Line-width

* Ui test.

* Final fixes.

* Fix build again.

* bring back ui test.

* Fix unsigned import.

* Another ui fix.

* Also refactor substrate-primitives

* Fix benchmarks.

* Fix doc test.

* fix doc tests

substrate/core/sr-primitives/src/generic/digest.rs

@@ -105,7 +105,7 @@ pub enum DigestItem<Hash> {
 impl<Hash: Encode> ::serde::Serialize for DigestItem<Hash> {
 	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: ::serde::Serializer {
 		self.using_encoded(|bytes| {
-			::substrate_primitives::bytes::serialize(bytes, seq)
+			::primitives::bytes::serialize(bytes, seq)
 		})
 	}
 }