Refactor: fixed point arithmetic for SRML. (#3456)

* Macro-ify perthings.

* Refactor fixed64

* Half-workign phragmen refactor.

* Finalize phragmen refactor.

* Fix creation of perquintill

* Fix build errors

* Line-width

* Fix more build errors.

* Line-width

* Fix offence test

* Resolve all TODOs.

* Apply suggestions from code review

Co-Authored-By: Gavin Wood <gavin@parity.io>
Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Fix most of the review comments.

* Updates to multiply by rational

* Fxi build

* Fix abs issue with Fixed64

* Fix tests and improvements.

* Fix build

* Remove more tests from staking.

* Review comments.

* Add fuzzing stuff.

* Better fuzzing

* Better doc.

* Bump.

* Master.into()

* A bit more hardening.

* Final nits.

* Update lock

* Fix indent.

* Revert lock file.

* Bump.

substrate/srml/offences/src/lib.rs

@@ -33,7 +33,7 @@ use support::{
 };
 use sr_primitives::{
 	Perbill,
-	traits::Hash,
+	traits::{Hash, Saturating},
 };
 use sr_staking_primitives::{
 	offence::{Offence, ReportOffence, Kind, OnOffenceHandler, OffenceDetails},
@@ -131,12 +131,9 @@ where
 				offenders_count.saturating_sub(previous_offenders_count),
 				validator_set_count,
 			);
-			let numerator = new_fraction
-				.into_parts()
-				.saturating_sub(previous_fraction.into_parts());
-			let denominator =
-				Perbill::from_parts(Perbill::one().into_parts() - previous_fraction.into_parts());
-			Perbill::from_parts(denominator * numerator)
+			let numerator = new_fraction.saturating_sub(previous_fraction);
+			let denominator = Perbill::one().saturating_sub(previous_fraction);
+			denominator.saturating_mul(numerator)
 		} else {
 			new_fraction.clone()
 		};