RNG list to be implemented

As discussed before, I'd like to implement various RNGs in this package. And temporarily they are listed in the following:

Four from [Random123](https://www.deshawresearch.com/resources_random123.html):
- [x] Threefry
- [x] Philox
- [x] AESNI
- [x] ARS

The [xorshift families](http://xoroshiro.di.unimi.it/):
- [x] xoroshiro128+
- [x] xorshift128+
- [x] xorshift1024*

Six from [SPRNG](http://www.sprng.org/)
- [ ] Combined Multiple Recursive Generator
- [ ] 48 Bit Linear Congruential Generator with Prime Addend
- [ ] 64 Bit Linear Congruential Generator with Prime Addend
- [ ] Modified Lagged Fibonacci Generator
- [ ] Multiplicative Lagged Fibonacci Generator
- [ ] Prime Modulus Linear Congruential Generator