Include object level in metadata field names

[clovis]

This change would require a careful inspection of all the code that relies on field names. One big advantage of this change would be that it would remove any ambiguity for a particular field that is used at different object levels. It would also do away with the generic div type, which causes no end of issues...
The head field would probably be the most affected. To evaluate if this change does not introduce more problems than it solves...