makeGWuClass -- constructor for unstable Grothendieck-Witt classes

The unstable Grothendieck-Witt class is represented by the data of a Grothendieck-Witt class and a non-zero element of the base field or finite étale algebra such that the determinant of the Gram matrix of the Grothendieck-Witt class must agree with the square of the non-zero element of the base field or finite étale algebra up to multiplication by a square.

The method makeGWuClass can be applied to a symmetric matrix or a Grothendieck-Witt class together with the data of a scalar, and it will automatically use the determinant of the matrix or Grothendieck-Witt class as the non-zero element of the base field or finite étale algebra if no such element is provided.

Over the complex numbers, real numbers, rational numbers, or finite fields of characteristic not 2, the constructor makeGWuClass verifies that the scalar, if provided, agrees with the determinant of the Gram matrix of the Grothendieck-Witt class or matrix up to multiplication by a square. Over arbitrary finite étale algebras over fields, the constructor will permit the construction of an unstable Grothendieck-Witt class with any nonzero scalar and warn the user to verify that the scalar agrees with the determinant of the matrix representative of the stable part up to squares.

Over an arbitrary finite étale algebra over a field, any nonzero algebra element can be used as the scalar in the construction of an unstable Grothendieck-Witt class. In cases when the user provides a scalar different from the determinant of the Gram matrix of the Grothendieck-Witt class or matrix, the user must manually verify that the scalar agrees with the determinant of the Gram matrix of the Grothendieck-Witt class or matrix up to multiplication by a square. In this case, a warning is printed: Warning, the function is not able to verify if the determinant of M and a agree up to squares..