dirmgr `changed` tracking
Currently there are parts of the dirmgr where we have functions that take a changed
boolean and must remember to update it. We even have places where changed
is saved and a inner changed
folded in.
This is straightforward albeit (ISTM) error-prone; it replaces a previous more principled arrangment which was too awkard to work with. I think it would be nice to reconsider if we could do better here. I will think about it.