We want to be able to build a representation of the dependency graph so
we can easily inspect it.
We do not want to make GraphML by default. It is better to use a tool.
We use "petgraph-graphml".
This begins providing release notes for changes and provides scripts to
facilitate this:
- tools/mkrelease will update RELEASES.md and run some checks.
- build-aux/release-check is intended for use in pipelines (e.g. see
.gitlab-ci.yml) to verify that releases were done properly.