labelled 2.11.0

Improvements

• set_value_labels(), add_value_labels(), remove_value_labels(),
  set_variable_labels(), set_na_range() and set_na_values() can now be
  applied on a vector (#126)
• new argument null_action for var_label() when applied on a
  data frame (#131)
• look_for() now returns "missing" (number of NAs) by default (#133)

Bug fixes

• bug fix in print.look_for() (#135)
• bug fix in unlabelled() for classic vectors, now remained unchanged (#137)