modelbased 0.15.0

Breaking Changes

• Argument join_dots in the plot() method, which is used to connect dots
  with lines, now defaults to FALSE.

Changes

• Support for models of class nestedLogit.

• estimate_contrasts() can now also calculate contrasts of average slopes, by
  defining two numeric predictors in the contrast argument. This can also be
  useful when estimating the context effects of within- and between-effects in a
  model.