Change structure of title generator plugin.

+ Use bundle hooks instead of label hooks, this enables modification of labels
  even when the user isn't adding or editing a label.
+ Labels are being removed and then re-added as editLabel() does not seem to
  work as expected.
Remove error_log() accidentally committed.
Merge branch 'TitleGeneratorUseBundleHooks' of github.com:leftclickben/providence into TitleGeneratorUseBundleHooks