CMGAMatrix

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   Computes the transfer matrix from gimbal rates to torques.

   t = a*[alphaDot(1);betaDot(1);...alphaDot(k);betaDot(k)]

   In the base frame the CMG momentum vector is [0;h;0]
   initialize           u.h        (n)      Scalar momentum
                        u.b        {n}(3,3) Transforms from CMG base to body 
                        u.alpha    (n)      Inner gimbal angles (rad)
                        u.beta     (n)      Outer gimbal angles (rad)

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   Form:
   y = CMGAMatrix( u )
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   Inputs
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   u             (1,1)   Data Structure

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   Outputs
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   y             (3,:)   Torque matrix

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