Fixed the tests

src/rotation.rs

@@ -133,6 +133,7 @@ pub trait Rotation3<S: BaseNum>: Rotation<S, Vector3<S>, Point3<S>>
 /// matrix:
 ///
 /// ```no_run
+/// #![feature(core)]
 /// use cgmath::rad;
 /// use cgmath::Vector2;
 /// use cgmath::{Matrix, ToMatrix2};

tests/quaternion.rs

@@ -13,6 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#![feature(core)]
 
 extern crate cgmath;