BUGFIX: loading data objects

Data objects were not loaded correctly because the bytes at the
beginning were read over and over again. The position is now increased
each time a double is read from the array.
BUGFIX: Saving Duplicates working

Needed a hack to correctly save the data objects in the duplicate.
First the duplicate ADDocument was created, then the data object for
each wrapper in the duplicate document was loaded from the file data in
the original document.
BUGFIX: Extra hack for saving duplicates of Unsaved documents

The duplicate copy did not work when the original document had never
been saved ('Untitled'). In that case, the data object in the original
file (which should be present as the file has not been incrementally
loaded yet) is serialized into binary data and that data is used to
create a copy of the data object which is then added to the duplicate
document.