ENH/BUG: Period and PeriodIndex ops supports timedelta-like
Merge pull request #7966 from sinhrks/period_delta

ENH/BUG: Period and PeriodIndex ops supports timedelta-like
API: add Series.dt delegator for datetimelike methods (GH7207)

CLN: make _add_delegate_accessors generic
Merge pull request #7953 from jreback/dt

API: add Series.dt delegator for datetimelike methods (GH7207)
COMPAT: raise SettingWithCopy in even more situations when a view is at hand
COMPAT: capture chain indexing even on single-dtyped
update to holiday to help with GH#7070
ENH: Use 'left' constructor on pd.merge

Use the _constructor property when creating the merge/ordered_merge result to
preserve the output type. Update test and docs appropriately.
BUG: Timestamp cannot parse nanosecond from string
Merge pull request #7907 from sinhrks/parse_ns2

BUG: Timestamp cannot parse nanosecond from string
Merge pull request #7913 from MichaelWS/master

update to holiday to help with GH#7070
Merge branch 'merge_constructor' of https://github.com/jwass/pandas into jwass-merge_constructor

Conflicts:
	doc/source/v0.15.0.txt
Merge pull request #7950 from jreback/setting_with_copy

COMPAT: raise SettingWithCopy in even more situations when a view is at hand
Categorical: preserve ints when NaN are present

`Categorical([1, np.nan])` would end up with a single `1.` float level.
This commit ensures that if `values` is a list of ints and contains np.nan,
the float conversation does not take place.
Categorical: fix describe with np.nan
Categorical: ensure that one can assign np.nan
Categorical: fix assigning NaN if NaN in levels
API: change default Categorical.from_codes() to ordered=False

In the normal constructor `ordered=True` is only assumed if the levels
are given or the values are sortable (which is most of the cases), but
in `from_codes(...)` we can't asssume this so the default should be
`False`.
Categorical: add some links to Categorical in the other docs
Categorical: use s.values when calling private methods

s.values is the underlying Categorical object, s.cat will be changed
to only expose the API methods/properties.