Updates optimised fork choice.

- Bug fixes in optimised fork choice.
- YAML tests functioning.
- Implement Clippy suggestions.
- Remove Copywrite notices.

eth2/fork_choice/src/longest_chain.rs

@@ -30,7 +30,7 @@ impl<T: ClientDB + Sized> ForkChoice for LongestChain<T> {
         &mut self,
         block: &BeaconBlock,
         block_hash: &Hash256,
-        spec: &ChainSpec,
+        _: &ChainSpec,
     ) -> Result<(), ForkChoiceError> {
         // add the block hash to head_block_hashes removing the parent if it exists
         self.head_block_hashes