Per-transaction weight for srml (#2799)

* debug checkpoint.

* new

* Worked.

* Worked and weight propagated to executive.

* Works with some tests.

* Cleanup debug prints.

* More cleanup.

* Undo more logs.

* Undo a few more.

* Fix build.

* Allow len to be used in weight calculation.

* Remove noop function from dispath.

* Cleanup.

* Unify traits.

* Update docs and nits.

* line width

* Update core/sr-primitives/src/weights.rs

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

* Update core/sr-primitives/src/weights.rs

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

* Update core/sr-primitives/src/weights.rs

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

* Update core/sr-primitives/src/weights.rs

Co-Authored-By: Amar Singh <asinghchrony@protonmail.com>

* Update srml/example/src/lib.rs

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

* Final cleanup.

* Fix build.

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

@@ -18,6 +18,7 @@
 //! stage.
 
 use crate::traits::{self, Member, SimpleArithmetic, MaybeDisplay};
+use crate::weights::{Weighable, Weight};
 
 /// Definition of something that the external world might want to say; its
 /// existence implies that it has been checked and is good, particularly with
@@ -32,8 +33,7 @@ pub struct CheckedExtrinsic<AccountId, Index, Call> {
 	pub function: Call,
 }
 
-impl<AccountId, Index, Call> traits::Applyable
-	for CheckedExtrinsic<AccountId, Index, Call>
+impl<AccountId, Index, Call> traits::Applyable for CheckedExtrinsic<AccountId, Index, Call>
 where
 	AccountId: Member + MaybeDisplay,
 	Index: Member + MaybeDisplay + SimpleArithmetic,
@@ -55,3 +55,12 @@ where
 		(self.function, self.signed.map(|x| x.0))
 	}
 }
+
+impl<AccountId, Index, Call> Weighable for CheckedExtrinsic<AccountId, Index, Call>
+where
+	Call: Weighable,
+{
+	fn weight(&self, len: usize) -> Weight {
+		self.function.weight(len)
+	}
+}