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   Computes the true anomaly from the eccentric or hyperbolic anomaly.
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   Form:
   nu = E2Nu( e, E )
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   ------
   Inputs
   ------
   e             (1,:)   Eccentricity
   E             (1,:)   Eccentric or Hyperbolic anomaly

   -------
   Outputs
   -------
   nu            (1,:)   True anomaly

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   References:   Bate, R. R., Fundamentals of Astrodynamics. pp. 20-40.
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