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/elections-phragmen/src/lib.rs

@@ -83,7 +83,10 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use sp_std::prelude::*;
-use sp_runtime::{print, DispatchResult, DispatchError, traits::{Zero, StaticLookup, Convert}};
+use sp_runtime::{
+	print, DispatchResult, DispatchError, Perbill,
+	traits::{Zero, StaticLookup, Convert},
+};
 use frame_support::{
 	decl_storage, decl_event, ensure, decl_module, decl_error, weights::SimpleDispatchInfo,
 	traits::{
@@ -637,7 +640,7 @@ impl<T: Trait> Module<T> {
 		let voters_and_votes = <VotesOf<T>>::enumerate()
 			.map(|(v, i)| (v, i))
 			.collect::<Vec<(T::AccountId, Vec<T::AccountId>)>>();
-		let maybe_phragmen_result = sp_phragmen::elect::<_, _, _, T::CurrencyToVote>(
+		let maybe_phragmen_result = sp_phragmen::elect::<_, _, _, T::CurrencyToVote, Perbill>(
 			num_to_elect,
 			0,
 			candidates,
@@ -664,7 +667,7 @@ impl<T: Trait> Module<T> {
 				.filter_map(|(m, a)| if a.is_zero() { None } else { Some(m) } )
 				.collect::<Vec<T::AccountId>>();
 
-			let support_map = sp_phragmen::build_support_map::<_, _, _, T::CurrencyToVote>(
+			let support_map = sp_phragmen::build_support_map::<_, _, _, T::CurrencyToVote, Perbill>(
 				&new_set,
 				&phragmen_result.assignments,
 				Self::locked_stake_of,