cheapr 1.3.1

Bug fixes

• Fixed a bug where recycle sometimes modified lists in-place.

• Fixed a rare issue that could in theory occur where -2147483648 would
  be recognised as a representable integer in R.

Changes

• attrs_add and attrs_rm have been renamed to attrs_modify and
  attrs_clear respectively to convey their intent more clearly.

• as_df now always returns a plain data.frame with only 3 attributes,
  'names', 'row.names' and 'class'.

New features

• df_modify as a fast way to modify and add columns to a data frame.