PLAT: platform sorting issue surfaced with time_grouper
Merge pull request #6649 from pydata/platform_sort

PLAT: platform sorting issue surfaced with time_grouper
DOC: update groupby pd.Grouper docs
CLN: move set_grouper/get_grouper type pd.Grouper methods to internal
Merge pull request #6655 from jreback/groupby

DOC/API: pd.Grouper docs / api
dataframe bar plot can now accept width and pos keywords for more flexible alignment