The interface of Int assumes the value is immutable but a reference to
its content is leaked through the BigInt() method, which is mutable.
This fix resolves the leak by:
making a copy of the *big.Int in MakeBigInt()
returning a copy of the *big.Int content in BigInt()
creating an internal method bigInt() for internal use that still
returns reference to the internal big.Int
The interface of Int assumes the value is immutable but a reference to its content is leaked through the BigInt() method, which is mutable. This fix resolves the leak by:
Fixes: #332