Euler/Quaternion conversion do not wrap over -90

[kkolyan]

Seems like it somewhere clamping to [90;-90]

    use cgmath::Deg;
    use cgmath::Euler;
    use cgmath::Quaternion;
    use cgmath::Rotation3;

    #[test]
    fn test1() {
        let b = Deg(-91.234);
        assert_eq!(b.0, -91.234);
        let q = Quaternion::from_angle_y(b);
        let c = Euler::from(q);
        /*
        assertion `left == right` failed
          left: -91.234°
         right: -90.0°
         */
        assert_eq!(Deg(-91.234), Deg::from(c.y))
    }

[kkolyan]

hm, in glam that works the same...

seems like the problem is missing EulerOrdering, which allows to deal with that.