Elliptic Curves over the Rational Field

New features:

• Implementation of the ``computing heights of points with little or no factorization'' algorithm.
• New functions EllipticLogarithm and pAdicEllipticLogarithm to compute the elliptic logarithm and p-adic elliptic logarithm of a point, respectively.
• Vastly improved rank calculations for elliptic curves with no two-torsion.
• New functions IntegralPoints and SIntegralPoints to compute integral points and S-integral points, respectively. New related functions IntegralQuarticPoints, SIntegralQuarticPoints, SIntegralLjunggrenPoints and SIntegralDesbovesPoints.