xoroshiro128+ random number generator

[Joseph Rushton Wakeling via Digitalmars-d-announce]

On Saturday, 30 April 2016 at 11:04:14 UTC, Joseph Rushton 
Wakeling wrote:
> On Saturday, 30 April 2016 at 08:54:39 UTC, Nordlöw wrote:
>> On Friday, 29 April 2016 at 21:40:49 UTC, Joseph Rushton 
>> Wakeling wrote:
>>> Spotted this reddit post the other day:
>>> https://www.reddit.com/r/programming/comments/4gtlfz/xoroshiro128_the_fastest_fullperiod_pseudorandom/
>>
>> @nogc :)
>
> Hah, nicely spotted :-)

More importantly, the public fields of this generator should 
include:

     enum ulong min = ulong.min;

     enum ulong max = ulong.max;

... otherwise it won't work with `uniform` or anything that 
depends on it.