CRAN submission

[n-kall]

Now that we've changed over to posterior rather than loo for the psis code, we could think about submitting to CRAN so that other packages could use the iwmm functionality. Specifically I'm thinking of priorsense and potentially loo itself. I think that iwmm could be used to fix stan-dev/loo/issues/209

I'm opening this issue mainly to keep track of the tasks we would need to do to get iwmm on CRAN.

[n-kall]

@topipa I'd like to submit priorsense to CRAN soon, but to do that iwmm would need to either be on CRAN itself or in a repository that is "CRAN-like". I think we could put iwmm on https://r-universe.dev/ which would then work as a repository for this case. What do you think? I've done the same for priorsense, and the process was quite straightforward.

[topipa]

@n-kall I think that's a good idea for now before getting iwmm to CRAN too eventually. I just created a new R universe and added iwmm there: https://topipa.r-universe.dev/iwmm. Let me know if there is anything else I can do to help with priorsense CRAN submission!

[n-kall]

Great, thank you! I think this will allow priorsense to be on CRAN now