Allow Vector3::Equal to use vector of tolerances

[osrf-migration]

Original report (archived issue) by John Hsu (Bitbucket: hsu, GitHub: hsu).

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Curently, the Vector3::Equal with tolerance check uses a single tolerance for all three elements.

Proposal to extend it by adding:

      /// \brief Equality test with tolerance vector.
      /// \param[in] _v the vector to compare to
      /// \param[in] _tol a vector containing equality tolerances.
      /// \return true if the elements of the vectors are equal within
      /// the tolerence specified by _tol.
      public: bool Equal(const Vector3 &_v, const Vector3 &_tol) const
      {
        return equal<T>(this->data[0], _v[0], _tol[0])
            && equal<T>(this->data[1], _v[1], _tol[1])
            && equal<T>(this->data[2], _v[2], _tol[2]);
      }

Based on discussion in pull request #82, we might need to extend it further with:

      public: bool NumericallyEqual(const Vector3 &_v, const Vector3 &_tol) const;
      public: bool RelativelyEqual(const Vector3 &_v, const Vector3 &_tol) const;

[osrf-migration]

Original comment by Michael Sherman (Bitbucket: sherm1).

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I don't think it would be useful to have elementwise tolerance because of the difficulty in supplying meaningful values for them. Having a relative tolerance available makes that largely unnecessary since that produces a different absolute tolerance for each element based on its size.