Implement a proper generic resolution in decl_storage! (#2913)

* Add failing test case

* move storage maps to blake2_128 (#2268)

* remove default hash, introduce twox_128 and blake2

* use blake2_128 & create ext_blake2_128

* refactor code

* add benchmark

* factorize generator

* fix

* parameterizable hasher

* some fix

* fix

* fix

* fix

* metadata

* fix

* remove debug print

* map -> blake2_256

* fix test

* fix test

* Apply suggestions from code review

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

* impl twox 128 concat (#2353)

* impl twox_128_concat

* comment addressed

* fix

* impl twox_128->64_concat

* fix test

* Fix compilation and cleanup some docs

* Lol

* Remove traits from storage types that are not generic

* Get instance test almost working as wanted

* Make `srml-support-test` compile again :)

* Fixes test of srml-support

* Fix compilation

* Break some lines

* Remove incorrect macro match arm

* Integrates review feedback

* Update documentation

* Fix compilation

substrate/srml/staking/src/tests.rs

@@ -257,7 +257,7 @@ fn max_unstake_threshold_works() {
 			validator_payment: 0,
 		});
 
-		<OfflineSlash<Test>>::put(Perbill::from_fraction(0.0001));
+		OfflineSlash::put(Perbill::from_fraction(0.0001));
 
 		// Report each user 1 more than the max_unstake_threshold
 		Staking::on_offline_validator(10, MAX_UNSTAKE_THRESHOLD as usize + 1);
@@ -696,7 +696,7 @@ fn nominators_also_get_slashed() {
 		assert_eq!(Staking::offline_slash_grace(), 0);
 		// Account 10 has not been reported offline
 		assert_eq!(Staking::slash_count(&10), 0);
-		<OfflineSlash<Test>>::put(Perbill::from_percent(12));
+		OfflineSlash::put(Perbill::from_percent(12));
 
 		// Set payee to controller
 		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));