Pure Perl module to test Math::BigInt with scalars

Changes for 2.001000 - 2023-11-13

• Fix rounding bug in bsqrt() in Math::BigInt. Also make bsqrt() upgrade only when necessary.
• Simplify and speed up bsqrt() (for computing the square root) in Math::BigFloat. The computation time now mainly depends on the desired accuracy, not the number of digits in the significand.
• Add support for using "div_scale" as import parameter, like this
• Add better argument checking when the "div_scale" value is set by the user.