brms 0.9.1

new features

• Allow the / symbol in group-level terms in
  the formula argument to indicate nested
  grouping structures.
• Allow to compute WAIC and LOO
  based on the pointwise log-likelihood using argument
  pointwise to substantially reduce memory requirements.

other changes

• Add horizontal lines to the errorbars in
  marginal_effects plots for factors.

bug fixes

• Fix a bug that could lead to a cryptic error
  message when changing some parts of the model
  formula using the update method.
• Fix a bug that could lead to an error when
  calling marginal_effects for predictors
  that were generated with the base::scale
  function thanks to Tom Wallis.
• Allow interactions of numeric and categorical
  predictors in marginal_effects to be passed
  to the effects argument in any order.
• Fix a bug that could lead to incorrect results
  of predict and related methods when called with
  newdata in models using the poly function
  thanks to Brock Ferguson.
• Make sure that user-specified factor contrasts
  are always applied in multivariate models.