Make subxt-core ready for publishing (#1508)

* Move Extrinsic decoding things to subxt_core and various tidy-ups

* A couple more fixes and fmt

* first pass moving tx logic to subxt_core

* cargo fmt

* fix wasm example

* clippy

* more clippy

* WIP Adding examples and such

* Move storage functionality more fully to subxt_core and nice examples for storage and txs

* Add example for events

* consistify how addresses/payloads are exposed in subxt-core and add runtime API fns

* Add runtime API core example

* fmt

* remove scale-info patch

* Add a little to the top level docs

* swap args around

* clippy

* cargo fmt and fix wasm-example

* doc fixes

* no-std-ise new subxt-core additions

* alloc, not core

* more no-std fixes

* A couple more fixes

* Add back extrinsic decode test

subxt/examples/setup_client_offline.rs

@@ -16,7 +16,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     };
 
     // 2. A runtime version (system_version constant on a Substrate node has these):
-    let runtime_version = subxt::client::RuntimeVersion::new(9370, 20);
+    let runtime_version = subxt::client::RuntimeVersion {
+        spec_version: 9370,
+        transaction_version: 20,
+    };
 
     // 3. Metadata (I'll load it from the downloaded metadata, but you can use
     //    `subxt metadata > file.scale` to download it):