title: How to rotate object around a point using quaternions?
body: <p>In my 3D application I store object's position in a vector and it's rotation around the origin in a quaternion. I need to rotate the object around a vector with an arbitrary origin. I tried converting the position - vectorOrigin and the rotation into a matrix, rotating the matrix and then extracting the position and rotation as a vector and a quaternion from the resulting matrix. The position comes up ok, but the rotation remains constant (the object rotates around the given vector but it always faces in the same direction).</p>
  
  <p>Is my method wrong or do I have a bug?</p>