[#1] Fixed up unused imports, docs, and tests.

src/quaternion.rs

@@ -8,10 +8,8 @@ use std::ops::{Add, Sub, Mul, Div, Neg};
 
 use crate::zero::Zero;
 use crate::one::One;
-use crate::real::Real;
-use crate::trig::Radian;
 use crate::trig::Trig;
-use crate::vector::{Vector, EuclideanVector, Vector3};
+use crate::vector::{EuclideanVector, Vector3};