Repot frame_support::traits; introduce some new currency stuff (#8435)

* Reservable, Transferrable Fungible(s), plus adapters.

* Repot into new dir

* Imbalances for Fungibles

* Repot and balanced fungible.

* Clean up names and bridge-over Imbalanced.

* Repot frame_support::trait. Finally.

* Make build.

* Docs

* Good errors

* Fix tests. Implement fungible::Inspect for Balances.

* Implement additional traits for Balances.

* Revert UI test "fixes"

* Fix UI error

* Fix UI test

* Fixes

* Update lock

* Grumbles

* Grumbles

* Fixes

Co-authored-by: Bastian Köcher <info@kchr.de>

substrate/frame/support/src/traits/randomness.rs

@@ -0,0 +1,54 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2019-2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Traits for dealing with on-chain randomness.
+
+/// A trait that is able to provide randomness.
+///
+/// Being a deterministic blockchain, real randomness is difficult to come by, different
+/// implementations of this trait will provide different security guarantees. At best,
+/// this will be randomness which was hard to predict a long time ago, but that has become
+/// easy to predict recently.
+pub trait Randomness<Output, BlockNumber> {
+	/// Get the most recently determined random seed, along with the time in the past
+	/// since when it was determinable by chain observers.
+	///
+	/// `subject` is a context identifier and allows you to get a different result to
+	/// other callers of this function; use it like `random(&b"my context"[..])`.
+	///
+	/// NOTE: The returned seed should only be used to distinguish commitments made before
+	/// the returned block number. If the block number is too early (i.e. commitments were
+	/// made afterwards), then ensure no further commitments may be made and repeatedly
+	/// call this on later blocks until the block number returned is later than the latest
+	/// commitment.
+	fn random(subject: &[u8]) -> (Output, BlockNumber);
+
+	/// Get the basic random seed.
+	///
+	/// In general you won't want to use this, but rather `Self::random` which allows
+	/// you to give a subject for the random result and whose value will be
+	/// independently low-influence random from any other such seeds.
+	///
+	/// NOTE: The returned seed should only be used to distinguish commitments made before
+	/// the returned block number. If the block number is too early (i.e. commitments were
+	/// made afterwards), then ensure no further commitments may be made and repeatedly
+	/// call this on later blocks until the block number returned is later than the latest
+	/// commitment.
+	fn random_seed() -> (Output, BlockNumber) {
+		Self::random(&[][..])
+	}
+}