* Parse `pkgname` from `PKGBUILD` via sourcing to cope with variables
* Allow overriding the container name to be able to re-use an existing
container
* Be verbose when installing packages during the image creation
* Add my GPG key to the pacman keyring (not nice to hard-code it in the
Dockerfile but good enough for now)
* Install ccache into the base image to support makepkg's ccache option
* Split syncing packages and execution of `makepkg` so syncing can be
avoided when only building source package
* Don't quote `CRE`, it is unlikely spaces are needed here and using
chained commands (e.g. `sudo …`) might be useful
* Add documentation
* Allow building Arch Linux packages within a "standard" container similar
to how `makechrootpkg` allows building packages within a systemd-nspawn
container
* Add a Dockerfile to create an Arch Linux image suitable for package
builds via `makepkg`
