Add missing Copy marker to Vec4

src/math/vec4.rs

@@ -4,7 +4,7 @@ use itertools::izip;
 
 use std::ops::{Add, AddAssign, Mul, MulAssign, Sub, SubAssign};
 
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Debug, Clone, Copy)]
 pub struct Vec4<T: Float> {
     pub coords: [T; 4],
 }