Investigate standardizing on Pandas datetime instead of Numpy datetime #187
Description
Brought up in meeting on Feb 25:
It is worth considering using the Pandas date time objects consistently, wherever we currently use a numpy.datetime64.
numpy.datetime64 does not include time zone information. The function to_pandas() has been modified to explicitly use a pandas.DatetimeIndex with TZ info (see pr #184); using a np.datetime64 as a Dataframe index implicitly creates one, anyway.
I'm not sure where np.datetime64 is used, but it should be investigated.