I am upgrading nakamoto to rust-bitcoin 0.30 and before we were using Uint256 type for implementing the target.

Now that the type was hidden under the Target type I noted that there is no way to
make math operations on the target in order to calculate a new one.

In particular, our previous code is the following, (the last_target is a Uint256

       let mut target = last_target;

        target = target.mul_u32(adjusted_timespan);
        target = target / Target::from_u64(params.pow_target_timespan).unwrap();

So I think that the target should allow to make the multiplication and the division
with the Target type in order to manipulate an object.

Any thought?

This was also discuss in here #1820