Added the Zero and One traits to sigils.

It looks like these may be removed from the standard library soon.

src/quaternion.rs

@@ -3,11 +3,12 @@
 //!
 //! [1]: https://en.wikipedia.org/wiki/Quaternion
 //! [2]: https://en.wikipedia.org/wiki/Dual_quaternion
-use std::num::{Zero, One};
 use std::ops::{Add, Sub, Mul, Div, Neg};
 
-use super::real::Real;
-use super::vector::{Vector, EuclideanVector, Vector3};
+use ::zero::Zero;
+use ::one::One;
+use ::real::Real;
+use ::vector::{Vector, EuclideanVector, Vector3};
 
 
 /// A Quaternion is a combination of a scalar and a vector