Standardization of the XML declaration in the exported PDI-XML

Standardization of the XML declaration in the exported PDI-XML
Exported XML should be standardized. All XMLs exported by DTM masters are UTF-8 encoded. Other master DTM's do not define encoding information in the header (default is UTF-8).
In the EthertCAT master DTM the wrong encoding was changed from UTF-16 to UTF-8 which now causes problems for one customer (B&R).

Short term solution for this branch is to define no encoding in the xml header. for our latest branch we still need a standardized definition.