Clippy clean (#536)

* Change into_iter to iter

* Fix clippy 'easy' warnings

* Clippy eth2/utils

* Add struct NetworkInfo

* Clippy for types, utils, and beacon_node/store/src/iters.rs

* Cargo fmt

* Change foo to my_foo

* Remove complex signature

* suppress clippy warning for unit_value in benches

* Use enumerate instead of iterating over range

* Allow trivially_copy_pass_by_ref in serde_utils

eth2/state_processing/src/per_block_processing/is_valid_indexed_attestation.rs

@@ -45,7 +45,7 @@ pub fn is_valid_indexed_attestation<T: EthSpec>(
     let check_sorted = |list: &[u64]| -> Result<()> {
         list.windows(2).enumerate().try_for_each(|(i, pair)| {
             if pair[0] >= pair[1] {
-                return Err(error(Invalid::BadValidatorIndicesOrdering(i)));
+                Err(error(Invalid::BadValidatorIndicesOrdering(i)))
             } else {
                 Ok(())
             }

eth2/state_processing/src/per_block_processing/tests.rs

@@ -31,8 +31,8 @@ fn invalid_block_header_state_slot() {
     let builder = get_builder(&spec);
     let (mut block, mut state) = builder.build(None, None, &spec);
 
-    state.slot = Slot::new(133713);
-    block.slot = Slot::new(424242);
+    state.slot = Slot::new(133_713);
+    block.slot = Slot::new(424_242);
 
     let result = per_block_processing(
         &mut state,

eth2/state_processing/src/per_block_processing/verify_attestation.rs

@@ -130,6 +130,6 @@ fn verify_casper_ffg_vote<'a, T: EthSpec>(
         );
         Ok(state.get_previous_crosslink(data.crosslink.shard)?)
     } else {
-        return Err(error(Invalid::BadTargetEpoch));
+        Err(error(Invalid::BadTargetEpoch))
     }
 }