BUG: already mixed indexes should not sort
FIX resample with fill_method and how #2073

DOC add to release notes
PERF: add dtype inference vbenches (GH7332)

PERF: recognize int64 to timedelta64[ns] conversions and perform faster

PERF: use names/kinds for dtype inference on known types

DOC: performance docs
COMPAT: tests compat with current timezones (pytz) (GH7339)
Merge pull request #7341 from cpcloud/hayd-gh2073

FIX: resample with fill_method and how #2073
Merge pull request #7343 from jreback/tz

COMPAT: tests compat with current timezones (pytz) (GH7339)
TST7337: Try to resolve windows test failures.
TST: windows 32-bit test comparisons fixed
Merge pull request #7342 from jreback/infer

PERF: better dtype inference for perf gains (GH7332)
Merge pull request #7327 from cpcloud/fix-unorderables-mixed-union

BUG: already mixed indexes should not sort
TST: windows 32-bit test comparisons fixed part 2
implement additional tests for groupby apply methods
simplify groupby's std method
add sem to nanops
add sem to aggregate methods
add sem to groupby
add sem to docs