mlr3 0.1.4

• Task$set_col_roles() and Task$set_row_roles() are now deprecated.
  Instead it is recommended for now to work with the lists Task$col_roles and
  Task$row_roles directly.
• Learner$predict_newdata() now works without argument task if the learner
  has been fitted with Learner$train() (#375).
• Names of column roles have been unified ("weights", "label",
  "stratify" and "groups" have been renamed).
• Replaced MeasureClassifF1 with MeasureClassifFScore and fixed a bug in the
  F1 performance calculation (#353). Thanks to @001ben for reporting.
• Stratification is now controlled via a task column role (was a parameter of
  class Resampling before).
• Added a S3 predict() method for class Learner to increase
  interoperability with other packages.
• Many objects now come with a $help() which opens the respective manual page.