message: Update links in quaternions.rs
  * Update link to Arcsynthesis tutorial about quaternions
  The old link no longer goes to a valid page, and it appears to be malicious.
  * Fix links in quaternion.rs
  Don't split the line between the [text] and (url) or they don't get turned into a link in docs.rs
diff: @@ -72,10 +72,8 @@ impl<S: BaseFloat> Quaternion<S> {
  ///
  /// Return the closest rotation that turns `src` vector into `dst`.
  ///
  - /// - [Related StackOverflow question]
  - /// (http://stackoverflow.com/questions/1171849/finding-quaternion-representing-the-rotation-from-one-vector-to-another)
  - /// - [Ogre implementation for normalized vectors]
  - /// (https://bitbucket.org/sinbad/ogre/src/9db75e3ba05c/OgreMain/include/OgreVector3.h?fileviewer=file-view-default#cl-651)
  + /// - [Related StackOverflow question](http://stackoverflow.com/questions/1171849/finding-quaternion-representing-the-rotation-from-one-vector-to-another)
  + /// - [Ogre implementation for normalized vectors](https://bitbucket.org/sinbad/ogre/src/9db75e3ba05c/OgreMain/include/OgreVector3.h?fileviewer=file-view-default#cl-651)
  pub fn from_arc(
  src: Vector3<S>,
  dst: Vector3<S>,
  @@ -132,10 +130,8 @@ impl<S: BaseFloat> Quaternion<S> {
  /// more advisable to use `nlerp` when you know your rotations are going
  /// to be small.
  ///
  - /// - [Understanding Slerp, Then Not Using It]
  - /// (http://number-none.com/product/Understanding%20Slerp,%20Then%20Not%20Using%20It/)
  - /// - [Arcsynthesis OpenGL tutorial]
  - /// (http://www.arcsynthesis.org/gltut/Positioning/Tut08%20Interpolation.html)
  + /// - [Understanding Slerp, Then Not Using It](http://number-none.com/product/Understanding%20Slerp,%20Then%20Not%20Using%20It/)
  + /// - [Arcsynthesis OpenGL tutorial](https://www.roiatalla.com/public/arcsynthesis/html/Positioning/Tut08%20Interpolation.html)
  pub fn slerp(self, mut other: Quaternion<S>, amount: S) -> Quaternion<S> {
  let mut dot = self.dot(other);
  let dot_threshold: S = cast(0.9995f64).unwrap();
  