Add support for rand()

[Azzaare]

It would be great to handle rand for (union of) intervals

Of course, there is an issue with opened and closed bounds and how to handle them, as most rng will a value within an opened/closed interval. However, I believe it is not statically an issue.

If this is a feature of interest, I can make a PR for that next month (or someone can do it before me :p). Otherwise, I will define the function in my project!

[omus]

I think it's totally reasonable to be able to sample from an Interval. Feel free to open an PR

[haberdashPI]

I have some old code from TimeSpans lying around that has most of the functionality needed for this: beacon-biosignals/TimeSpans.jl#11