BUG: Fix broken YearBegin offset. Closes #2844.
BUG: Fix corner case in YearBegin
STY: Remove unnecessary old code.
BUG: Append the empty frame with columns, #3121
TST: Use correct expectations for AS in tests
API: return None when inplace=True. re #1893
CLN: clarify message for deprecated  #2918 df._verbose_info_
DOC: minor cookbook/io doc corrections
ENH: handle ragged CSV files nicely when specifying explicit list of column names. close #2981
BUG: stacking with MultiIndex column with some unused level uniques fails #3170
BUG: remove unused columns from final result
TST: PeriodIndex pickle roundtrip does not recreate freq GH2891
BUG: PeriodIndex pickle roundtrip does not recreate freq GH2891
Merge pull request #3224 from y-p/GH2891

PeriodIndex pickle roundtrip does not recreate freq GH2891
ENH index diff respects names
DOC: update RELEASE.rst
BLD: Compact builds to fit into travis's 5-job concurrency limit
DOC: update CONTRIBUTING.md
BUG: GH3216 Upcast when needed to DataFrame when setitem with indexer
ENH: On a mixed DataFrame, allow setting with indexers with ndarray/DataFrame on rhs
Merge pull request #3219 from jreback/GH3216

BUG: GH3216 Upcast when needed to DataFrame when setitem with indexer