newdoc without doctype

[buhtz]

See this from your docu

# create a new text document
doc = ezodf.newdoc(doctype='odt', filename='text.odt')
# or open an existing text document
doc = ezodf.opendoc('text.odt')

opendoc doesn't need a doctype because it recoginize it from the filename or the filecontent. newdoc shouldn't need doctype, too. Because it can recoginize the needed type from the filename suffix.

doctype should be optional (per default None)