brms 2.0.0

This is the second major release of brms. The main
new feature are generalized multivariate models, which now
support everything already possible in univariate models,
but with multiple response variables. Further, the internal
structure of the package has been improved considerably to be
easier to maintain and extend in the future.
In addition, most deprecated functionality and arguments have
been removed to provide a clean new start for the package.
Models fitted with brms 1.0 or higher should remain
fully compatible with brms 2.0.

new features

• Add support for generalized multivariate models,
  where each of the univariate models may have a different
  family and autocorrelation structure.
  Residual correlations can be estimated for multivariate
  gaussian and student models. All features
  supported in univariate models are now also available in
  multivariate models. (#3)
• Specify different formulas for different
  categories in categorical models.
• Add weakly informative default priors for the
  parameter class Intercept to improve convergence
  of more complex distributional models.
• Optionally display the MC standard error in the
  summary output. (#280)
• Add argument re.form as an alias of
  re_formula to the methods posterior_predict,
  posterior_linpred, and predictive_error
  for consistency with other packages making use of
  these methods. (#283)

other changes

• Refactor many parts of the package to make
  it more consistent and easier to extend.
• Show the link functions of all
  distributional parameters in the summary
  output. (#277)
• Reduce working memory requirements when
  extracting posterior samples for use in predict
  and related methods thanks to Fanyi Zhang. (#224)
• Remove deprecated aliases of functions
  and arguments from the package. (#278)
• No longer support certain prior specifications,
  which were previously labeled as deprecated.
• Remove the depreacted addition term
  disp from the package.
• Remove old versions of methods fixef,
  ranef, coef, and VarCorr.
• No longer support models fitted with brms < 1.0,
  which used the multivariate 'trait' syntax
  orginally deprecated in brms 1.0.
• Make posterior sample extraction in the
  summary method cleaner and less error prone.
• No longer fix the seed for random number generation
  in brm to avoid unexpected behavior in simulation studies.

bug fixes

• Store stan_funs in brmsfit objects
  to allow using update on models with user-defined
  Stan functions thanks to Tom Wallis. (#288)
• Fix problems in various post-processing methods
  when applied to models with the reserved variable
  intercept in group-level terms thanks to
  the GitHub user ASKurz. (#279)
• Fix an unexpected error in predict and related
  methods when setting sample_new_levels = "gaussian"
  in models with only one group-level effect.
  Thanks to Timothy Mastny. (#286)