brms 2.13.3

New Features

• Fix shape parameters across multiple monotonic terms via argument
  id in function mo to ensure conditionally monotonic effects. (#924)
• Support package rtdists as additional backend of wiener
  distribution functions thanks to the help of Henrik Singmann. (#385)

Bug Fixes

• Fix generated Stan Code of models with improper global priors and
  constant priors on some coefficients thanks to Frank Weber. (#919)
• Fix a bug in conditional_effects occuring for categorical
  models with matrix predictors thanks to Jamie Cranston. (#933)

Other Changes

• Adjust behavior of the rate addition term so that it also
  affects the shape parameter in negbinomial models thanks to
  Edward Abraham. (#915)
• Adjust the default inverse-gamma prior on length-scale parameters
  of Gaussian processes to be less extreme in edge cases thanks
  to Topi Paananen.