FIX raise when groupby selecting cols not in frame
PERF: dataframe.from_records: read into list w/ itertools.islice when specifying nrows #6700
EHN/FIX: Add na_position parameter to DataFrame.sort. Fixes GH3917
TST: Skip mergesort test if `np.argsort` raises TypeError on any mergesort.
Merge pull request #5231 from unutbu/nan-sort

EHN/FIX: Add na_last parameter to DataFrame.sort. Fixes GH3917
BUG: Bug in consistency of groupby aggregation when passing a custom function (GH6715)
COMPAT: change Series.sort to use na_position rather than deprecated na_last
BUG: shift now converts named axis to numer. fixes #6724
TST: test named shift with named axis
Merge pull request #6725 from dalejung/shift_named_axis

Shift named axis
Merge pull request #6718 from jreback/groupby_agg

BUG: Bug in consistency of groupby aggregation when passing a custom function (GH6715)
TST: Added tests for pairwise behaviour in rolling moments.

Added a test for rolling_cov_pairwise similar to the test for
rolling_corr_pairwise.

Added tests for ewmcov_pairwise and ewmcorr_pairwise.

Added test for expanding_cov_pairwise based on the test for
expanding_corr_pairwise.
ENH: Implemented pairwise rolling moment functions.

Implemented rolling_cov_pairwise function.

Implemented ewmcov_pairwise and ewmcorr_pairwise.

Implemented expanding_cov_pairwise.

Refactored the rolling moment functions to use _flex_pairwise_moment.
ENH: Folded the *_pairwise rolling moment functions into the base function API.
DOC: Updated documentation for pairwise API changes.

Added a release note and example usage for pairwise=True.
ENH: Marked rolling_corr_pairwise and expanding_corr_pairwise as deprecated.
added percentage rank to DataFrame.Rank
Merge pull request #4950 from snth/pairwise

Pairwise versions for rolling_cov, ewmcov and expanding_cov
Merge pull request #6728 from MichaelWS/master

added percentage rank to DataFrame.Rank
SQL: add index_label keyword to to_sql
Merge pull request #6642 from jorisvandenbossche/sql-multiindex

SQL: add index_label keyword to to_sql
BUG: bug in BlockManager._get_numeric_data, with invalid combine