Call Partition_AddModuleObject when initializing the python module.
Fixes bug when using the Partition class but the class has not
been added to the module via Py_TypeReady.
A common error was the type not being ready (missing attributes):
>>> for pa in cxt.parts:
... print(pa.partno)
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
AttributeError: 'libfdisk.Partition' object has no attribute 'partno'
Jose M. Guisado Gomez