Pure Perl module to test Math::BigInt with scalars

Changes for 2.000000 - 2023-10-29

• Merge the Math-BigRat distribution into the Math-BigInt distribution. This merge eliminates the problems that users have experienced when incompatible versions of the two distributions have been installed. This fixes CPAN RT #143228.
• Add method from_dec() to Math::BigRat to make Math::BigRat more consistent with Math::BigInt and Math::BigFloat.
• To be consistent with Math::BigInt and Math::BigFloat, make it possible to use "require" with Math::BigRat, e.g.,