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   Compute inertial position and velocity given circular orbit elements
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   Form:
   [r,v] = CircularOrbitState( R, inc, ra, M, n );
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   Inputs
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   R          (1,:)    Distance from planet center 
   inc        (1,1)    Inclination [rad]
   ra         (1,1)    Right ascension [rad]
   M          (1,:)    Mean anomaly [rad]
   mu         (1,:)    Gravitational constant for planet (optional)
                       If not provided, mu for Earth is used.

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   Outputs
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   lat         (1)       Latitude  [deg]
   lon         (1)       Longitude [deg]
   alt         (1)       Altitude  [km]

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