Roughed in support for user-supplied structMaps in direct upload CONTENTdm DIP packages.
Changed '= None' and '!= None' to 'is None' and 'is not None'.
Changed back erroneously introduced 'is None' to '= None' in assignment statements.
Completed support for user-supplied structMaps in direct upload compound CONTENTdm DIPs. Also removed some obsolete @todo comments.