recursion in model.TableModel.headerData

[Former user]

After deleting a lot of nodes, the model won't update properly.

Traceback (most recent call last):
  File "H:/.nuke\python\NodeTable\model.py", line 855, in headerData
    if section >= len(self.knob_list):
RuntimeError: maximum recursion depth exceeded

[Mitja Müller-Jend]

e4e294a