BUG: fix plotting of dup indexed objects
Merge pull request #4495 from Komnomnomnom/tox-pytz

BLD/TST: correct pytz version for tox
Merge pull request #4492 from cpcloud/plotting-length-fix

BUG: fix plotting of dup indexed objects
BUG: allow cummethods to work with bool dtypes
Merge pull request #4440 from cpcloud/fix-cumsum-bool

BUG: allow cumprod and cumsum to work with bool dtypes
BUG: (GH4016) fix panel slicing issue that was returning an object that should not
     have be a reduction in ndim
BUG: (GH3830), panel assignment using loc with a transpose frame did not work
ER: GH3777, raise a NotImplementedError for Panel -> Panel setting with alignment
Merge pull request #4507 from jreback/panel_index

BUG/ER: various panel indexing fixes
TST: tests for GH4502, consistency in ix assignments, but ok in master
Merge pull request #4509 from jreback/ix_consist

TST: tests for GH4502, consistency in ix assignments, but ok in master
CLN: do not allow frozenset
Merge pull request #4482 from cpcloud/set-construct

BUG: raise on frozenset construction by Series
DOC: cookbook example
DOC: added google finance as a data source to the DataReader doc
DOC: corrected cookbook.rst example on reversing timeseries
BUG: GH4516 Fixed issue with sorting a duplicate multi-index that has multiple dtypes
Merge pull request #4518 from mehyar/doc_datareader

DOC: added google finance as a data source to the DataReader doc
Merge pull request #4522 from jreback/mi_dups

BUG: GH4516 Fixed issue with sorting a duplicate multi-index that has multiple dtypes
DOC: add more docs to CONTRIBUTING