Replace "coin" with "network"

The Processor's coins folder referred to the networks it could process, as did
its Coin trait. This, and other similar cases throughout the codebase, have now
been corrected.

Also corrects dated documentation for a key pair is confirmed under the
validator-sets pallet.

substrate/client/src/networks/monero.rs

@@ -0,0 +1,101 @@
+use core::str::FromStr;
+
+use scale::{Encode, Decode};
+
+use ciphersuite::{Ciphersuite, Ed25519};
+
+use monero_serai::wallet::address::{AddressError, Network, AddressType, AddressMeta, MoneroAddress};
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Address(MoneroAddress);
+impl Address {
+  pub fn new(address: MoneroAddress) -> Option<Address> {
+    if address.payment_id().is_some() {
+      return None;
+    }
+    Some(Address(address))
+  }
+}
+
+impl FromStr for Address {
+  type Err = AddressError;
+  fn from_str(str: &str) -> Result<Address, AddressError> {
+    MoneroAddress::from_str(Network::Mainnet, str).map(Address)
+  }
+}
+
+impl ToString for Address {
+  fn to_string(&self) -> String {
+    self.0.to_string()
+  }
+}
+
+// SCALE-encoded variant of Monero addresses.
+#[derive(Clone, PartialEq, Eq, Debug, Encode, Decode)]
+enum EncodedAddressType {
+  Standard,
+  Subaddress,
+  Featured(u8),
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Encode, Decode)]
+struct EncodedAddress {
+  kind: EncodedAddressType,
+  spend: [u8; 32],
+  view: [u8; 32],
+}
+
+impl TryFrom<Vec<u8>> for Address {
+  type Error = ();
+  fn try_from(data: Vec<u8>) -> Result<Address, ()> {
+    // Decode as SCALE
+    let addr = EncodedAddress::decode(&mut data.as_ref()).map_err(|_| ())?;
+    // Convert over
+    Ok(Address(MoneroAddress::new(
+      AddressMeta::new(
+        Network::Mainnet,
+        match addr.kind {
+          EncodedAddressType::Standard => AddressType::Standard,
+          EncodedAddressType::Subaddress => AddressType::Subaddress,
+          EncodedAddressType::Featured(flags) => {
+            let subaddress = (flags & 1) != 0;
+            let integrated = (flags & (1 << 1)) != 0;
+            let guaranteed = (flags & (1 << 2)) != 0;
+            if integrated {
+              Err(())?;
+            }
+            AddressType::Featured { subaddress, payment_id: None, guaranteed }
+          }
+        },
+      ),
+      Ed25519::read_G::<&[u8]>(&mut addr.spend.as_ref()).map_err(|_| ())?.0,
+      Ed25519::read_G::<&[u8]>(&mut addr.view.as_ref()).map_err(|_| ())?.0,
+    )))
+  }
+}
+
+#[allow(clippy::from_over_into)]
+impl Into<MoneroAddress> for Address {
+  fn into(self) -> MoneroAddress {
+    self.0
+  }
+}
+
+#[allow(clippy::from_over_into)]
+impl Into<Vec<u8>> for Address {
+  fn into(self) -> Vec<u8> {
+    EncodedAddress {
+      kind: match self.0.meta.kind {
+        AddressType::Standard => EncodedAddressType::Standard,
+        AddressType::Subaddress => EncodedAddressType::Subaddress,
+        AddressType::Integrated(_) => panic!("integrated address became Serai Monero address"),
+        AddressType::Featured { subaddress, payment_id: _, guaranteed } => {
+          EncodedAddressType::Featured(u8::from(subaddress) + (u8::from(guaranteed) << 2))
+        }
+      },
+      spend: self.0.spend.compress().0,
+      view: self.0.view.compress().0,
+    }
+    .encode()
+  }
+}