Python API documentation updates: a description of class hierarchy

was added to the docstrings of most Python extension types.

source/blender/freestyle/intern/python/Interface1D/FEdge/BPy_FEdgeSmooth.cpp

@@ -12,6 +12,8 @@ extern "C" {
 //------------------------INSTANCE METHODS ----------------------------------
 
 static char FEdgeSmooth___doc__[] =
+"Class hierarchy: :class:`Interface1D` > :class:`FEdge` > :class:`FEdgeSmooth`\n"
+"\n"
 "Class defining a smooth edge.  This kind of edge typically runs across\n"
 "a face of the input mesh.  It can be a silhouette, a ridge or valley,\n"
 "a suggestive contour.\n"