------------------
New features:
- Support env var PLONE_RELEASER_MULTI_PACKAGES to signal doing multiple releases.
We still change `checkouts.cfg` and `versions.cfg` in the relevant coredev branches then,
but we do not offer to push them.
[maurits] (37)
Bug fixes:
- Fixed detecting changes in packages that are missing from checkouts.
[maurits] (35)