Add individual processing for ef tests (#745)

* Add Individual signature verification for ef tests

* Add clone state to avoid errors in ef tests

* Add state verification for VerifyIndividual in ef tests

* Add Clone derive for errors

* Update comments

eth2/utils/cached_tree_hash/src/lib.rs

@@ -10,7 +10,7 @@ pub use crate::multi_cache::MultiTreeHashCache;
 use ethereum_types::H256 as Hash256;
 use tree_hash::TreeHash;
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum Error {
     /// Attempting to provide more than 2^depth leaves to a Merkle tree is disallowed.
     TooManyLeaves,

eth2/utils/ssz_types/src/lib.rs

@@ -53,7 +53,7 @@ pub mod length {
 }
 
 /// Returned when an item encounters an error.
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Debug, Clone)]
 pub enum Error {
     OutOfBounds {
         i: usize,