labelled 2.13.0

New features

• add a null_action argument to val_labels(), val_label() and a
  .null_action argument to set_value_labels(), add_value_labels() and
  remove_value_labels() (#145)
• new functions update_variable_labels_with() and update_value_labels_with()
  allowing to update variable/value labels with a custom function (#153)

Bug fix

• avoid an error with print.look_for() when console pane is physically shrunk
  too small (#148)
• fix in recode.haven_labelled() when .x contains NA and
  .combine_value_labels = TRUE (#151)
• produce an error when trying to assign value labels to a Date vector (#156)