Use EncodeLike for storages traits (#3676)

* impl

* patch

* lock

* some refactor

* some avoided copy

* new api without ref for doublemap

* fix

* version bump

* fix

* point to incoming release

* use codec latest

* bumpd impl version

* fix unused

* fix

* Update srml/support/src/storage/mod.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/srml/scored-pool/src/lib.rs

@@ -88,7 +88,7 @@ mod mock;
 #[cfg(test)]
 mod tests;
 
-use codec::{Encode, Decode};
+use codec::FullCodec;
 use rstd::prelude::*;
 use support::{
 	StorageValue, StorageMap, decl_module, decl_storage, decl_event, ensure,
@@ -117,7 +117,7 @@ pub trait Trait<I=DefaultInstance>: system::Trait {
 	type Currency: Currency<Self::AccountId> + ReservableCurrency<Self::AccountId>;
 
 	/// The score attributed to a member or candidate.
-	type Score: SimpleArithmetic + Clone + Copy + Default + Encode + Decode + MaybeSerializeDebug;
+	type Score: SimpleArithmetic + Clone + Copy + Default + FullCodec + MaybeSerializeDebug;
 
 	/// The overarching event type.
 	type Event: From<Event<Self, I>> + Into<<Self as system::Trait>::Event>;