OrbitKFRHS

-------------------------------------------------------------------------------
   Computes the right-hand-side of the orbit equations about a mass point
-------------------------------------------------------------------------------
   Form:
   xDot = OrbitKFRHS( x, t, d, q )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   x         (:,1)     The state vector [x;p]
   t                   Time
   d         (1,1)     Data structure
    		  			.dFName     (:,1)   Derivative function
    			  		.nStates            Number of elements in the state vector
   					  ...               Data for derivative function
   q                   Plant noise matrix

   -------
   Outputs
   -------
   x         (:,1)     The state vector derivative[xDot;pDot]

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