BUG: Fix DatetimeIndex.insert() with non-datetimes.

Coerces to object Index instead.
COMPAT: allow string concats to datetimeindex only (int/float are invalid)
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
BUG: use the "join" string in Appender decorator

The docstring for Appender decorator says that "join" parameter is used to join the docstring and addendum.  This commit brings the code in line with the documentation.
PERF: add np.max and np.min to _cython_table (GH5927)
BLD: travis ensures tarball can be installed without cython
BLD: pip wheel support is stable, travis can use the provided version
Merge pull request #5966 from y-p/PR_travis_cython_check

Pr travis cython check
Merge pull request #5962 from cancan101/fix_nat_tz

BUG: Fixed to_datetime for array with both Tz-aware datetimes and NaTs
Update rolling skew & kurtosis to handle cases where they aren't defined

The rolling skewness and kurtosis in algos.pyx were modified to match
the testing logic in pandas/core/nanops.py. They now both return NaN
where they are not defined, which occurs where there are either too
few observations or where the variance is zero.

A set of tests was added to verify that Nan is returned in these cases
and that the computations continue to work correctly when the values
are defined.
Merge pull request #5760 from yieldsfalsehood/master

Update rolling skew & kurtosis to handle cases where they aren't defined
Merge pull request #5960 from dsm054/more_resample_fast_paths

PERF: add np.max and np.min to _cython_table (GH5927)
PERF: perf improvments in dtypes/ftypes methods (GH5968)
Merge pull request #5970 from jreback/dtypes_perf

PERF: perf improvments in dtypes/ftypes methods (GH5968)