Python API documentation updates: a description of class hierarchy

was added to the docstrings of most Python extension types.

source/blender/freestyle/intern/python/UnaryFunction1D/BPy_UnaryFunction1DDouble.cpp

@@ -114,6 +114,8 @@ int UnaryFunction1DDouble_Init( PyObject *module ) {
 //------------------------INSTANCE METHODS ----------------------------------
 
 static char UnaryFunction1DDouble___doc__[] =
+"Class hierarchy: :class:`UnaryFunction1D` > :class:`UnaryFunction1DDouble`\n"
+"\n"
 "Base class for unary functions (functors) that work on\n"
 ":class:`Interface1D` and return a float value.\n"
 "\n"