Python API documentation updates: a description of class hierarchy

was added to the docstrings of most Python extension types.

source/blender/freestyle/intern/python/StrokeShader/BPy_ThicknessVariationPatternShader.cpp

@@ -12,6 +12,8 @@ extern "C" {
 //------------------------INSTANCE METHODS ----------------------------------
 
 static char ThicknessVariationPatternShader___doc__[] =
+"Class hierarchy: :class:`StrokeShader` > :class:`ThicknessVariationPatternShader`\n"
+"\n"
 "[Thickness shader]\n"
 "\n"
 ".. method:: __init__(pattern_name, iMinThickness, iMaxThickness, stretch)\n"