Update futuremice

[thomvolker]

Implements the following changes:

• Allow for user-specified functions or the use of auxiliary packages within futuremice.
• Initialize random seed of this has not happened before.
• Add function for core checking and use smarter n.core specification

[thomvolker]

This pull request would solve #139, #529, #533 and #544. Additionally, #542 can be closed as per the regular futuremice() functionality.

[gerkovink]

@thomvolker do the checks pass on your machine?

[thomvolker]

I don't think I can run these checks locally. devtools::check() indicated some issues with the convergence() function, but I did not make any adjustments to that. These checks seem to indicate problems with my R version (4.3.0), but given the problems I experienced over the past few days with R not working, I won't switch back to older versions. Perhaps, if you still have an older R version running, you can try to rebuild the package?

[gerkovink]

I meant the windows one, not the Unix ones. I'll rebuild and rerun the checks. Thanks

[thomvolker]

Thanks! I now see that the checks also didn't pass after @stefvanbuuren's latest update (see https://github.com/amices/mice/actions/runs/3673696826).

[stefvanbuuren]

I just updated the GitHub action script. mice 3.15.2 now gets its five green balls.

[thomvolker]

Great! Do you want me to resolve the conflicts that now occured because of changing the description and news?

[stefvanbuuren]

Yes. Please incorporate the changes of mice 3.15.2. Do not increase the version number in the PR as I want to restrict version increases to the master. So put your news above the 3.15.2 news and after merge I will create v3.15.+.

[thomvolker]

Then I think everything is now set, but let me know if there are other changes that have to be made first.