WIP: Automation

[krlmlr]

Closes #27.

[pat-s]

I used this branch today again for a CRAN release and it (still) worked great (with all changes from main).

I would be interested in putting work in to get this merged. What do you think @krlmlr?

[krlmlr]

Great it works for you. Same here.

Before merging, I think we want to:

• replace devtools::submit_cran() with a home-grown solution
• replace usethis::use_github_release() with a home-grown solution
• ensure that existing tests pass
• add new tests if possible
• document the release process

Let's aim for a merge in late Q1.

[krlmlr]

Let's merge this into the main branch. There remain a few rough edges, I'll file issues.

@maelle: This adds pre_release(), release() and post_release() functions that automate the CRAN release process as much as possible. We always open a new branch cran-x.y.z and immediately update the main branch to version x.y.z.9000 -- this ensures that a CRAN release never blocks further development and that GitHub install will always give a 9xxx version. Curious to hear your thoughts.

[pat-s]

Merging this huge PR and refining in small chunks sounds good to me.

Excited to see this getting merged!