Also split the iterator vs. file log message ids, so that they
are used only in one place each.

OutOfZone is used in the ZoneFinder for other class of errors
and we can't really bring it into the ZoneValidationException
hierarchy.

... instead of MasterLoadError.

 commit.

This fixes build issues discovered during code review.

Add a new constructor to name, one that takes an optional origin and completes
relative names with it.

Also clarify the '@' handling as a side effect.