impl traits from num-traits for UInt

[vxpm]

also adds a new trait PrimNumber which has an extra trait bound of num_traits::PrimInt for both the trait itself and the UnderlyingType nevermind, not a good idea. the trait implementations are enough

[danlehmann]

Hey, sorry I've been so slow to getting to this.

First of all: Thank you for your contribution!

This patch needs tests that actually exercise the new functionality.

I think, some things won't actually compile

                fn to_i64(&self) -> Option<i64> {
                    self.value().try_into().ok()
                }

My guess is that this will fail in the try_into() if the underlying type is u128. So we'd need tests for both u10 and u100.

[dzmitry-lahoda]

@vxpm would you have time to recheck this ? thank you