Check docs and run clippy on PRs (#326)

* Check docs, clippy, test run

* test parallel CI adapted from other package; is it faster?

* Remember to download substrate

* Nightly for cargo fmt

* Standardise CI names

* fix clippy complaints

* Ensure docs are valid and export publicly accessible types

* all-targets clippy, and fix additional lint errors

* newline in ci file

src/subscription.rs

@@ -391,9 +391,9 @@ mod tests {
                                 ]
                                 .into_iter(),
                             )),
-                            block: block_filter.clone(),
-                            extrinsic: extrinsic_filter.clone(),
-                            event: event_filter.clone(),
+                            block: block_filter,
+                            extrinsic: extrinsic_filter,
+                            event: event_filter,
                             events: Default::default(),
                             finished: false,
                         };