DOC: release notes corrections

TST: argmin/max impl, tests, and doc-strings
API: raise on __nonzero__ for Index (GH7897)
Merge pull request #7951 from jreback/index_follow

DOC/TST: index followup
ENH: New `level` argument for DataFrame.tz_localize and DataFrame.tz_convert (GH7846)
Merge pull request #7915 from mtrbean/ENH-7846

ENH: New `level` argument for DataFrame.tz_localize and DataFrame.tz_convert (GH7846)
TST: windows fixes relatd to Index not-subclass-ndarray
Removed unpaired left-paren.  Rephrased references.
Merge pull request #7959 from mcjcode/docfix

DOC: Removed unpaired right-paren.  Rephrased references.
DOC: cookbook.rst update
ENH/BUG: Period and PeriodIndex ops supports timedelta-like
BUG: fix transform with integers
Merge pull request #7973 from cpcloud/transform-oddity-7972

BUG: fix transform with integers
PERF: perf improvements for Series.transform (revised) (GH6496)
Merge pull request #7975 from jreback/transform_perf

PERF: perf improvements for Series.transform (revised) (GH6496)
BUG: Allow __name__less callables as groupby hows (GH7929)
Merge pull request #7974 from dsm054/allow_nameless_callables

BUG: Allow __name__less callables as groupby hows (GH7929)
INT: use platform_int for np.repeat related (GH7975)
Merge pull request #7966 from sinhrks/period_delta

ENH/BUG: Period and PeriodIndex ops supports timedelta-like
Fix DataFrame.to_latex() with MultiIndex columns

Currently, the positioning of \midrule is determined by the number of index
levels, not columns levels:

	>>> print pd.DataFrame({('x', 'y'): ['a']}).to_latex()
	\begin{tabular}{ll}
	\toprule
	{} &  x \\
	\midrule
	{} &  y \\
	0 &  a \\
	\bottomrule
	\end{tabular}

The fix is simple: use the number of column levels instead of the number
of index levels.
API: add Series.dt delegator for datetimelike methods (GH7207)

CLN: make _add_delegate_accessors generic