BLD: erase local ipython_directive
BLD: pull in latest ipython_directive from ipython 0355d3d
BLD: ipython_directive, add back okexcept
BLD: ipython_directive, enforce tight layout for mpl plots
BLD: ipython_directive, cython magic fix
BLD: make io.rst utf8-safe GH5142 GH5926
BLD: ipython_directive, decode ipython output as utf8+replace
Merge pull request #5925 from y-p/PR_rebase_ipython_directive

Rebase ipython_directive on top of recent ipython updated version
DOC: document read_csv fastpath for iso8601 datetime strings
Merge pull request #5993 from y-p/PR_doc_iso8601_fast_path

DOC: document read_csv fastpath for iso8601 datetime strings
ENH: improved inference of timedelta64[ns] and datetime64[ns] in the prescence NaT/None/NaN
     from object dtypes (GH5689)
CLN: refactor of timedelta routines to cython for inclusion in maybe_convert_objects
BUG: apply to a Series with a timedelta (GH5458)
ENH: improved timedelta inference for non-ns dtypes
BUG: timedelta64 merge/join issues (GH5695)
DOC: release note for timedelta changes
TST: skip tests on numpy < 1.7 as needed for timedeltas