Per-things trait. (#4904)

* Give perthigns the trait it always deserved.

* Make staking and phragmen work with the new generic per_thing

* Make everything work together 🔨

* a bit of cleanup

* Clean usage

* Bump.

* Fix name

* fix grumbles

* hopefully fix the ui test

* Some grumbles

* revamp traits again

* Better naming again.

substrate/frame/randomness-collective-flip/src/lib.rs

@@ -154,7 +154,9 @@ mod tests {
 	use super::*;
 	use sp_core::H256;
 	use sp_runtime::{
-		Perbill, traits::{BlakeTwo256, OnInitialize, Header as _, IdentityLookup}, testing::Header,
+		Perbill,
+		testing::Header,
+		traits::{BlakeTwo256, OnInitialize, Header as _, IdentityLookup},
 	};
 	use frame_support::{impl_outer_origin, parameter_types, weights::Weight, traits::Randomness};