Make one_of work with list of non-generators

[spicychickensauce]

(from: #209)
I'm using this construct quite often, maybe one_of could be made to support non-generator containing lists as an argument directly?

StreamData.one_of(things |> Enum.map(&StreamData.constant/1))

It already works if all the items are atoms, since those are already automatically generators.

iex(3)> StreamData.one_of([:foo, :bar, :baz]) |> Enum.take(2)
[:foo, :foo]

I don't know if it makes sense to special case one_of. Maybe it's possible to make all non-generators automatically constant generators like already done for atoms and tuples? What would be the consequences of this more drastic change?

[whatyouhide]

I forgot that we have member_of 🙃

[spicychickensauce]

Oops, don't know how I missed that. Thanks for pointing it out!