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
ENH/CLN: add HistPlot class inheriting MPLPlot
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
Merge pull request #7809 from sinhrks/histplot

ENH/CLN: add HistPlot class inheriting MPLPlot