rlp serialization refactor (#4873)

* fixed naming of rlp modules

* RlpStream cleanup

* appending short rlp lists (0...55 bytes) is 25% faster

* RlpStream does not use bytes module, nor trait Stream

* removed unused code from rlp module

* compiling ethcore-util with new rlp serialization

* compiling parity with new rlp serialization

* fixed compiling ethcore-light with new rlp serialization

* fixed compiling ethsync with new rlp serialization

* removed redundant comment, print

* removed redundant double-space

* replace usage of WriteBytesExt with ByteOrder

sync/src/chain.rs

@@ -2177,7 +2177,7 @@ mod tests {
 	use util::sha3::Hashable;
 	use util::hash::H256;
 	use util::bytes::Bytes;
-	use rlp::{Rlp, RlpStream, UntrustedRlp, View, Stream};
+	use rlp::{Rlp, RlpStream, UntrustedRlp, View};
 	use super::*;
 	use ::SyncConfig;
 	use super::{PeerInfo, PeerAsking};