Automate NEWS generation

Created by: matthijskooijman

The NEWS has a high-level changelog, which is currently manually written at release time (or sometimes in chunks between releases).

I would like to investigate a scheme were changelog entries are written along with the code changes (i.e. as part of the pull request). An obvious way would be to just modify the NEWS file in a commit inside the PR, but that is going to cause a lot of conflicts, and makes it harder to include the PR number in the changelog).

An obvious way would be to just use the git log to generate the changelog, but IMHO that would produce a too finegrained changelog. e.g. for NEWS it useful to know a bug was fixed, but there is no need to know that three refactoring commits were needed before that. Also, if you want the git log, you can just use git or github to see it.

So ideally, you would explicitly add a message to each PR description (or selected commit messages), which are then automatically generated into a NEWS file at releasetime with some script (probably with some chance to do manual post-processing if needed).

It seems there are quite some tools for this. Reading through this article, Changelox looked promising, but their website is giving an SSL failure right now. The github-changelog-generator project also has a list of competitors that might prove useful.

For the upcoming 3.0.2 release, the changelog is simple enough to just do it manually as before, but I'd like to see if we can set up something like this for the next release cycle.