- converting to and from dateTime.iso8601
- converting cat_id-arrays to and from xmlrpc structs with cat-id / name pairs (and creating & updateing new cats)
2) removed unnecessary (and not standard conform) xmlrpc struc arround all responses
3) added detection to copy arrays (numerical keys 0,1,...) to xmlrpc arrays and not structs
Note: 2+3 only apply to the _php class as the _epi class does this by itself