Implement UniformSampler for Wrapping<T>

[pitdicker]

This is the commit from #436 that we delayed until after the 0.5 release.

[pitdicker]

r @vks?

[dhardy]

You really like writing code, don't you? 😄 I just wonder whether this will actually be useful to many people, same as how you didn't like the updated rand_derive thing.

[vks]

What is the use case of this? I can't really think of a reason why you want want to sample from a wrapped range.

[dhardy]

Since users don't normally need to look at the impl docs when using Uniform, it's not even obvious that this handles low > high differently. Often for users it will be enough to just sample integers, then "wrap" afterwards (if there is actually any reason to want to sample wrapping integers from a restricted range). So unless there is a really good use-case for this code I think we should just forget it, sorry.

[pitdicker]

What is the use case of this?

I guess I got carried away a bit when implementing Standard for Wrapping<T> and though implementing Uniform would be nice to.

For a wrapping type I think it makes sense to be able to sample from a range that wraps around, but no, I can't see many uses. In a way it would be "sample from the entire range of the type, except between [high, low)".