Merge pull request #4610 from jreback/series_reindex

CLN: refactor Series.reindex to core/generic
ENH: Keep original traceback in DataFrame.apply

When "raise <exception instance>" is used inside a try/except block, the
original stacktrace (containing the code path that raised the original
exception).  This makes debugging difficult since all we know is that an error
occured when `frame._apply_standard` attempted to call the provided function.
Preserve the original stacktrace by using "raise" instead of "raise <exception
instance>".  This facilitates debugginb by allowing us to see where (in the
provided callable) the exception occured.

Added mention of this change in release notes
Merge pull request #4549 from bburan-galenea/bburan-galenea/apply_exception_traceback

ENH/API: Keep original traceback in DataFrame.apply
BUG: Fix selection with ``ix/loc`` and non_unique selectors (GH4619)
Merge pull request #4622 from jreback/ix_issue

BUG: Fix selection with ``ix/loc`` and non_unique selectors (GH4619)
TST: GH4312, assignment with iloc/loc and an dtype change
BUG: Fix assignment with iloc/loc involving a dtype change in an existing column (GH4312)
TST: add tests/test_generic.py

API/CLN: Refactor rename methods to core/generic.py; fixes Series.rename for (GH4605), and adds rename
   with the same signature for ``Panel``

API/CLN: Refactor Series.copy to core/generic.py; removes the order argument from Series.copy (inconsistent)
Merge pull request #4624 from jreback/astype_iloc2

API/CLN: setitem in Series now consistent with DataFrame
Merge pull request #4627 from jreback/rename_consist

API/CLN: make rename and copy consistent across NDFrame
Merge pull request #4499 from Komnomnomnom/moments-doc-

DOC: fix conflicting ewma documentation
BLD: test_perf, bring back pickle-compare code clobbered in 244d56751
BLD: test_perf, revert s/save/to_pickle change, warn the unwary
Merge pull request #4644 from y-p/PR_test_perf_fixes

test_perf fixes, restore clobbered pickle compare cmdargs, restore back_compat
BUG: Test and fix for subclasses of CacheableOffset (GH4609)
PERF: optimize __getitem__ in DataFrame for columns lookup
Merge pull request #4639 from jreback/gi_perf

PERF: optimize __getitem__ in DataFrame for columns lookup
ENH: (GH4629) Support for using a DatetimeIndex/PeriodsIndex directly in a datelike calculation
     e.g. s-s.index
BUG: Boolean indexing on an empty series loses index names
DOC add fix status for 4235