Allow modules to validate transaction, second attempt (#2463)

* first impl

* rename origin::inherent to none

* fix

* fix

* Apply suggestions from code review

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* comment

* better error

* doc

* (add unsigned module 🤦)

* doc

* fix

* implement for node-template as well

* add validated unsigned to executor

* fix

* fix

* bump version

* testing xt

* remove extraneous logic

* licence

* impl test

substrate/srml/support/test/tests/instance.rs

@@ -75,14 +75,14 @@ mod system {
 	pub enum RawOrigin<AccountId> {
 		Root,
 		Signed(AccountId),
-		Inherent,
+		None,
 	}
 
 	impl<AccountId> From<Option<AccountId>> for RawOrigin<AccountId> {
 		fn from(s: Option<AccountId>) -> RawOrigin<AccountId> {
 			match s {
 				Some(who) => RawOrigin::Signed(who),
-				None => RawOrigin::Inherent,
+				None => RawOrigin::None,
 			}
 		}
 	}