Added exponentiation to Natural
Unit test will cover both Natural implementations
Add >=,> and <= operators to Natural
Added Natural.random method
Added & operator to Natural
Added bool operator to Natural
Added in-place right shift operator to Natural
Added size_in_bits() method to Natural
Added support for str() method to Natural
Add even/odd operator to Natural
Miller-Rabin test
Add is_perfect_square method to Natural
Simplify GMP code with _as_parameter_
Added jacobi_symbol method to Natural
Lucas test
merge in jacobi
Add multiplication to Natural