Merge pull request #3548 from jreback/GH3546

BUG: Fixed bug in selecting month/quarter/year from a series would not select correctly (GH3546)
Merge pull request #3531 from jreback/hdf_bug

ENH: HDFStore enhancements
BUG: GH3416 properly convert np.datetime64 objects in the _possibily_convert_datetimes
CLN: _possibily_convert_datetimes now uses to_datetimes internally
BUG: fixes GH3425, raising on passed invalid dtypes for datetimelike

     fixes GH2423, astyping is now checked when using datetimelike and timedeltalike
     for valid astype to dtypes

BUG: PY3 compat for timedelta64[ns] in astype

BUG: more py3 compat

PTF