Error message for not existing charter

Created by: GVogeler

To avoid too many XRX-errors in the user interface a formally correct link like "http://monasterium.net/mom/IlluminierteUrkunden/1345_Chelmsford/charter" which cannot be resolved to an atom:id could return an error message 'Unfortunately there is no charter in MOM-CA with this identifier.' Best if additionally there is a link to the collection/fond in which the charters could be included.