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

Coerces to object Index instead.
COMPAT: allow string concats to datetimeindex only (int/float are invalid)
BLD: Explicitly request utf-8 encoding in docs conf.py (is default)
DOC: suppress warning during doc building
BUG: Bug in pd.read_msgpack with inferring a DateTimeIndex frequencey
     incorrectly (GH5947)
CLN: repr_html raises NotImplementedError rather then ValueError in qtconsole GH5922
Merge pull request #5948 from jreback/msgpack_bug

BUG: Bug in pd.read_msgpack with inferring a DateTimeIndex frequency incorrectly (GH5947)
DOC: move _templates out of source/ files to avoid warning
DOC: disable running monkey patch example through ipython_directive

Makes line numbering break in following documents run through sphinx.
Very strange,
Merge pull request #5953 from y-p/PR_doc_fixes

Misc fixes to doc build
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 #5951 from y-p/PR_latest_ipython_rep_fixes

CLN: repr_html raises NotImplementedError rather then ValueError in qtconsole
Merge pull request #5944 from unutbu/str-extract

ENH: Improve perf of str_extract
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.