tidyr 0.5.0

New functions

• separate_rows() separates observations with multiple delimited values into
  separate rows (#69, @aaronwolen).

Bug fixes and minor improvements

• complete() preserves grouping created by dplyr (#168).
• expand() (and hence complete()) preserves the ordered attribute of
  factors (#165).
• full_seq() preserve attributes for dates and date/times (#156),
  and sequences no longer need to start at 0.
• gather() can now gather together list columns (#175), and
  gather_.data.frame(na.rm = TRUE) now only removes missing values
  if they're actually present (#173).
• nest() returns correct output if every variable is nested (#186).
• separate() fills from right-to-left (not left-to-right!) when fill = "left"
  (#170, @dgrtwo).
• separate() and unite() now automatically drop removed variables from
  grouping (#159, #177).
• spread() gains a sep argument. If not-null, this will name columns
  as "keyvalue". Additionally, if sep is NULL missing values will be
  converted to <NA> (#68).
• spread() works in the presence of list-columns (#199)
• unnest() works with non-syntactic names (#190).
• unnest() gains a sep argument. If non-null, this will rename the
  columns of nested data frames to include both the original column name,
  and the nested column name, separated by .sep (#184).
• unnest() gains .id argument that works the same way as bind_rows().
  This is useful if you have a named list of data frames or vectors (#125).
• Moved in useful sample datasets from the DSR package.
• Made compatible with both dplyr 0.4 and 0.5.
• tidyr functions that create new columns are more aggresive about re-encoding
  the column names as UTF-8.