add_actor does not respect headers

[soad003]

The add actors feature helps adding linking tags to actors. It does this by completely overriding the tagpack with new data. Unfortunately the routine is not header aware that means all properties defined in the header file are written to the tagpack and the link to the header is removed if a tagpack is update by add_actor.

It would be nicer if the routine would keep the rev to the headerfile intact.