Rename vec_shuffle to fisher_yates_shuffle

We're adding another shuffler so it's nice to be specific

Cargo.toml

@@ -11,7 +11,7 @@ members = [
 	"eth2/utils/honey-badger-split",
 	"eth2/utils/slot_clock",
 	"eth2/utils/ssz",
-	"eth2/utils/vec_shuffle",
+	"eth2/utils/fisher_yates_shuffle",
 	"beacon_node",
 	"beacon_node/db",
 	"beacon_node/beacon_chain",

eth2/types/Cargo.toml

@@ -18,4 +18,4 @@ serde_derive = "1.0"
 serde_json = "1.0"
 slog = "^2.2.3"
 ssz = { path = "../utils/ssz" }
-vec_shuffle = { path = "../utils/vec_shuffle" }
+fisher_yates_shuffle = { path = "../utils/fisher_yates_shuffle" }

eth2/types/src/beacon_state.rs

@@ -5,12 +5,12 @@ use crate::{
     PendingAttestation, PublicKey, Signature, Slot, Validator,
 };
 use bls::verify_proof_of_possession;
+use fisher_yates_shuffle::shuffle;
 use honey_badger_split::SplitExt;
 use rand::RngCore;
 use serde_derive::Serialize;
 use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
 use std::ops::Range;
-use vec_shuffle::shuffle;
 
 pub enum Error {
     InsufficientValidators,

eth2/utils/fisher_yates_shuffle/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "vec_shuffle"
+name = "fisher_yates_shuffle"
 version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"