When a new method is added to Math::BigInt or Math::BigFloat, and this new
method requires a new backend library method, die with a suitable error
message if the installed backend library does not support this new method.
The error message says that the method requires a newer version of the
backend library.Fix typos in Math::BigFloat and Math::BigInt.
Add bfib() and blucas() to Math::BigInt. They return Fibonacci and Lucas
numbers, respectively. The actual computation of the numbers is done by the
backend library. Documented both methods in POD. Add test files bfib-mbi.t
and blucas-mbi.t.Add _fib() and _lucas() to Math::BigInt::Lib. They return Fibonacci and
Lucas numbers, respectively. Document both methods in POD. Add test files
author-lib-arithmetic-unary-_fib.t and author-lib-arithmetic-unary-_lucas.t.