Staking support (#99)

* Initial Staking API

* Add more staking types

* Reformat

* Remove dead code

* Fix missing documentation

* Reformat

* Staking: use proc macros

* Add partial session support

* Reformat

* Try to implement nomination

This currently fails with compilation errors I do not understand.

* Use the #[module] macro

This fixes a compile error

* Explain undefined method diagnostics

* Use ‘#[module]’ and implement session for Kusama

* Don’t impl ‘Staking’ for all ‘T: System’

* Add staking payout support

* Fix compilation errors and remove useless lifetimes

* Respond to code review

This fixes most of the issues found during review, with the exception of
tests.

* Make signing fallable and asynchronous

This is needed for hardware wallets, which require human confirmation to
sign transactions.  Blocking on a human to sign transactions is not a
good idea, and the signing might fail for many reasons (device
unplugged, authorization not granted, etc).

* Reformat

* Refactor as suggested by Andrew Jones (@ascjones).

* Reformat

* Refactor as suggested by Andrew Jones (@ascjones).

* Trait cleanups

* Make the `Signer` impl require Send + Sync

This is what Ledgeracio needs.

* Use the correct key for staking maps

They use the key type, not ‘PhantomData’.

* Implement set_payee call

* Switch to associated types for Staking

* Implement `set_keys`

This is needed for Ledgeracio.

* Remove impl of Signer for Box<dyn Signer + Send + Sync>

It isn’t needed, since Box implements Deref.

* Fix Polkadot and Kusama ‘SessionKey’ structs

I had failed to include the ‘Parachains’ component, which the default
Substrate runtime doesn’t have.

* Include a copy of `ValidatorId`

This avoids needing to depend on Polkadot.

* Fix syntax error in Cargo.toml

* Fix compile errors

* Add Debug impls

* Fix return type of `BondedStore`

* Use some upstream type definitions

Also add `Default` impls.

* Bump deps and fix build

* Remove last reference to Kusama feature

* Fix compilation errors

* Implement the `concat` in `twox_64_concat`

* Expose properties and per-era preferences

* Era rewards point support

I also did some refactoring.

* Expose clipped exposure

* Era reward points support

* Make `PayoutStakersCall` public

* Add in all default features for debugging

* Chill support and update to latest Substrate

* If property fetch fails, use dummy values

* Fix tests

* Fix header

* Remove some code Ledgeracio does not need

* More deletions

* Remove more code not needed for Ledgeracio

* Remove a pointless change in Cargo.toml

w.r.t. upstream.

* Remove more junk

* Revert contracts put_code test to pure code (not using the macro)

* Test contract instantiate

* Fmt

* WIP

* Add some more submission tests

* Reformat

* More tests

* Cleanup

* Hopefully fix CI

* Remove dead code

* Test chill

* Add missing docs

* Remove unnecessary use

* Revert "Remove unnecessary use"

This reverts commit bc8bc36bde581f1892ea88a778dfe0fe5bff24d7.

* Retry on temporary failures

* Ignore the staking tests on CI

* Obey the fmt

* Run CI with at most one test thread

* Implement tests for staking

* More tests

* Remove unhelpful println!

* Revert changes in contract tests

* Reformat

* Remove spurious diff

* More tests

Co-authored-by: Demi M. Obenour <demiobenour@gmail.com>
Co-authored-by: David Palm <dvdplm@gmail.com>
Co-authored-by: Andrew Jones <ascjones@gmail.com>

src/rpc.rs

@@ -96,6 +96,18 @@ impl From<u32> for BlockNumber {
     }
 }
 
+#[derive(serde::Serialize, serde::Deserialize, Debug, Clone, PartialEq, Eq, Default)]
+#[serde(rename_all = "camelCase")]
+/// System properties for a Substrate-based runtime
+pub struct SystemProperties {
+    /// The address format
+    pub ss58_format: u8,
+    /// The number of digits after the decimal point in the native token
+    pub token_decimals: u8,
+    /// The symbol of the native token
+    pub token_symbol: String,
+}
+
 /// Client for substrate rpc interfaces
 pub struct Rpc<T: Runtime> {
     client: Client,
@@ -208,6 +220,14 @@ impl<T: Runtime> Rpc<T> {
         Ok(metadata)
     }
 
+    /// Fetch system properties
+    pub async fn system_properties(&self) -> Result<SystemProperties, Error> {
+        Ok(self
+            .client
+            .request("system_properties", Params::None)
+            .await?)
+    }
+
     /// Get a header
     pub async fn header(
         &self,