1st draft of complete class-based std.random successor

[bearophile]

monarch_dodra:

> I think there is 0 doubt that reference semantics is the way to 
> go.

I agree.


> Furthermore, even in terms of performance, I think a heap 
> allocated PRNG will still flat-out beat the value based one, if 
> only because of the size of the damn thing.

OK.


>> Do you have a simple but very fast function that generates 
>> uniforms in [0.0, 1.0]? :-)
>
> AFAIK, the allocation issue is only for ranges?

Here I was not talking about allocations:
https://d.puremagic.com/issues/show_bug.cgi?id=5240

Bye,
bearophile