------------------------------------------------------------------------
   Computes angular rate from the equation mDot = m*Skew(w)
------------------------------------------------------------------------
   Form:
   w = RateFromDQ( q, qOld, dT )
------------------------------------------------------------------------

   ------
   Inputs
   ------
   q          (4,1)         Quaternion
   qOld       (4,1)         Last quaternion
   dT         (1,1)         Time step

   -------
   Outputs
   -------
   w          (3,1)         Rate (rad/sec)

------------------------------------------------------------------------