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
BUG: Timestamp cannot parse nanosecond from string