Add rand safe version of Poisson and Negative binomial distributions
#886
| Job | Run time |
|---|---|
| 17m 13s | |
| 13m 2s | |
| 12m 32s | |
| 19m 14s | |
| 11m 48s | |
| 10m 41s | |
| 1h 24m 30s |