Release v0.2.13

multimput 0.2.13

• aggregate_impute() handles the corner case when join results in an empty
  dataset.
• The model_fun argument of model_impute() can be either a function or a
  string containing the name of a function (like "glm").
  Include the package name in case the function is not available in base R (like
  "INLA::inla").