• Math::BigInt::Calc->_nok(): Use symmetry property nok(n,k) = nok(n,n-k) to
  speed up execution when k is large. Also general code cleanup. (Peter John
  Acklam).
  
• Math::BigInt::Calc->_gcd(): Speed up by reducing amount of data copying
  (Peter John Acklam).
  
• Add '01load.t' for basic module loading and diagnostics useful for
  debugging. Rename '00-signature.t' to '00sig.t', 'pod.t' to '02pod.t', and
  'pod_cov.t' to '03podcov.t' (Peter John Acklam).
  
• Math::BigInt:: Make from_hex(), from_oct(), and behave more like hex() and
  oct() in the Perl core, and make from_bin() consistent with from_hex() and
  from_oct() (this is related to RT #58954) (Peter John Acklam).
  
• Math::BigInt::Calc->_rem(): Modify first input arg always, not just
  sometimes (Peter John Acklam).
  
• Math::BigInt::Calc->_modinv(): be more consistent with the _modinv() method
  in other libraries (Math::BigInt::GMP, etc.) (Peter John Acklam)
  
• Math::BigInt::Calc->_nok(): use symmetry property nok(n,k) = nok(n,n-k).
  This cuts computation time tremendously when n and k are large (Peter John
  Acklam).
  
• Math::BigInt::Calc->_gcd(): quickly handle zero cases, avoid code
  duplication, and always modify the first input argument in-place (Peter John
  Acklam).
  
• Clean up code and add more code comments (Peter John Acklam).
  
• Fix typos (Peter John Acklam).