Adding a few univariate distributions.

[lrnv]

Hey,

Writing up the frailty representation of Archimedean copulas in Copulas.jl, I wrote a few univariate distributions samplers:

• Logarithmic distribution
• Sibuya distribution

There is also an Alpha stable distributions, but this is not my code and instead code from https://github.com/org-arl/AlphaStableDistributions.jl, which already stated that they will not consider merging into Distributions.jl (see org-arl/AlphaStableDistributions.jl#18)

They are fairly standard distributions. Would you want these distributions to be moved to Distributions.jl, or do I keep them into Copulas.jl ? They lack a few methods for the moment, but I could add some.

[ParadaCarleton]

I'd love to see these added! Feel free to make a PR so we can evaluate and merge it.

[lrnv]

Thanks !

A little overburden these days (wrapping up my Phd), but be sure I'll do this whenever I find some time to work on Copulas.jl again.