Initial mechanics for 80:20 fee split (#2912)

* Initial mechanics for 80:20 fee split

Also:
- Introduce extra functions for Imbalance manipulation;
- Store treasury pot in an account, letting total issuance account for
  it.

* Fix some tests

* Fix some tests

* Minor cleanups

* Update parity-codec version (#2855)

* Update parity-codec version

* Update grandpa, rhododendron and trie-bench

* Use primitive-types from crates.io

* Bump impl version

* Fix trie-bench version

* Fix lock files

* Fix versions

* Update codec to 4.1

* merge fix

* Revert merge

* More reversions

* Remove accidental code

* Update locks

* Bump runtime

* Update locks

* Tweaks and label TODO

* Update srml/treasury/src/lib.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Update issue number

* Update core/sr-primitives/src/traits.rs

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

* Fix wasm build

* Fix subkey build

substrate/core/sr-primitives/src/lib.rs

@@ -69,6 +69,14 @@ pub type Justification = Vec<u8>;
 
 use traits::{Verify, Lazy};
 
+/// A module identifier. These are per module and should be stored in a registry somewhere.
+#[derive(Clone, Copy, Eq, PartialEq, Encode, Decode)]
+pub struct ModuleId(pub [u8; 8]);
+
+impl traits::TypeId for ModuleId {
+	const TYPE_ID: [u8; 4] = *b"modl";
+}
+
 /// A String that is a `&'static str` on `no_std` and a `Cow<'static, str>` on `std`.
 #[cfg(feature = "std")]
 pub type RuntimeString = ::std::borrow::Cow<'static, str>;

substrate/core/sr-primitives/src/traits.rs

@@ -830,6 +830,110 @@ pub trait OpaqueKeys: Clone {
 	fn ownership_proof_is_valid(&self, _proof: &[u8]) -> bool { true }
 }
 
+struct TrailingZeroInput<'a>(&'a [u8]);
+impl<'a> codec::Input for TrailingZeroInput<'a> {
+	fn read(&mut self, into: &mut [u8]) -> usize {
+		let len = into.len().min(self.0.len());
+		into[..len].copy_from_slice(&self.0[..len]);
+		for i in &mut into[len..] {
+			*i = 0;
+		}
+		self.0 = &self.0[len..];
+		into.len()
+	}
+}
+
+/// This type can be converted into and possibly from an AccountId (which itself is generic).
+pub trait AccountIdConversion<AccountId>: Sized {
+	/// Convert into an account ID. This is infallible.
+	fn into_account(&self) -> AccountId;
+
+	/// Try to convert an account ID into this type. Might not succeed.
+	fn try_from_account(a: &AccountId) -> Option<Self>;
+}
+
+/// Provide a simply 4 byte identifier for a type.
+pub trait TypeId {
+	/// Simple 4 byte identifier.
+	const TYPE_ID: [u8; 4];
+}
+
+/// Format is TYPE_ID ++ encode(parachain ID) ++ 00.... where 00... is indefinite trailing zeroes to fill AccountId.
+impl<T: Encode + Decode + Default, Id: Encode + Decode + TypeId> AccountIdConversion<T> for Id {
+	fn into_account(&self) -> T {
+		(Id::TYPE_ID, self).using_encoded(|b|
+			T::decode(&mut TrailingZeroInput(b))
+		).unwrap_or_default()
+	}
+
+	fn try_from_account(x: &T) -> Option<Self> {
+		x.using_encoded(|d| {
+			if &d[0..4] != Id::TYPE_ID { return None }
+			let mut cursor = &d[4..];
+			let result = Decode::decode(&mut cursor)?;
+			if cursor.iter().all(|x| *x == 0) {
+				Some(result)
+			} else {
+				None
+			}
+		})
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::AccountIdConversion;
+	use crate::codec::{Encode, Decode};
+
+	#[derive(Encode, Decode, Default, PartialEq, Debug)]
+	struct U32Value(u32);
+	impl super::TypeId for U32Value {
+		const TYPE_ID: [u8; 4] = [0x0d, 0xf0, 0xfe, 0xca];
+	}
+	// cafef00d
+
+	#[derive(Encode, Decode, Default, PartialEq, Debug)]
+	struct U16Value(u16);
+	impl super::TypeId for U16Value {
+		const TYPE_ID: [u8; 4] = [0xfe, 0xca, 0x0d, 0xf0];
+	}
+	// f00dcafe
+
+	type AccountId = u64;
+
+	#[test]
+	fn into_account_should_work() {
+		let r: AccountId = U32Value::into_account(&U32Value(0xdeadbeef));
+		assert_eq!(r, 0x_deadbeef_cafef00d);
+	}
+
+	#[test]
+	fn try_from_account_should_work() {
+		let r = U32Value::try_from_account(&0x_deadbeef_cafef00d_u64);
+		assert_eq!(r.unwrap(), U32Value(0xdeadbeef));
+	}
+
+	#[test]
+	fn into_account_with_fill_should_work() {
+		let r: AccountId = U16Value::into_account(&U16Value(0xc0da));
+		assert_eq!(r, 0x_0000_c0da_f00dcafe);
+	}
+
+	#[test]
+	fn try_from_account_with_fill_should_work() {
+		let r = U16Value::try_from_account(&0x0000_c0da_f00dcafe_u64);
+		assert_eq!(r.unwrap(), U16Value(0xc0da));
+	}
+
+	#[test]
+	fn bad_try_from_account_should_fail() {
+		let r = U16Value::try_from_account(&0x0000_c0de_baadcafe_u64);
+		assert!(r.is_none());
+		let r = U16Value::try_from_account(&0x0100_c0da_f00dcafe_u64);
+		assert!(r.is_none());
+	}
+}
+
 /// Calls a given macro a number of times with a set of fixed params and an incrementing numeral.
 /// e.g.
 /// ```nocompile