So far, whenever a Python object is created from its corresponding C++ object, the input object reference is copied into a new object. Due to Freestyle's functions (especially regarding the way it is iterated), it is currently impossible to deal with a pointer-based Python object. It is not a real drawback, just an aspect to keep in mind.
From now on, when a set should be output (PySet_Type), it is given as a list (PyList_Type). The reason is that it doesn't really matter what we bring back to the Python interpreter. The set is guaranteed in memory on the C++ side.
For the CurvePoint class, the userdata variable is not yet ported (and will probably available as a list or a dictionary). The CurvePoint implementation works except for the initialization from other CurvePoints: somehow, the inner variables don't seem to be correctly handled. I do not know if it is a bug in Freestyle or if the CurvePoint object's state is correct for my test case. CurvePoint needs more testing.
Interface0DIterator was modified to allow BPy_Interface1D to be instantiated: verticesBegin(), verticesEnd(), pointsBegin(float) and pointsEnd(float) are not pure virtual functions anymore. If they are called directly from BPy_Interface1D (instead of its subclasses), an error message is displayed.