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

Coerces to object Index instead.
COMPAT: allow string concats to datetimeindex only (int/float are invalid)
Merge pull request #5833 from jreback/release

DOC: change doc refs to 0.13.1
DOC: added tutorials.rst template
DOC: whatsnew entries for ecosystem and tutorials
DOC: minor fix in extract docstring
DOC: tweaks
DOC: tweak ecosystem section
DOC: tweak ecosystem section
DOC: tweak ecosystem section
DOC: tweak ecosystem section
BLD: fix cythonized msgpack extension in setup.py GH5831
Merge pull request #5838 from danielballan/extract-docstring

DOC: minor fix in extract docstring
ENH: Improve error message for PeriodIndex to infer_freq. Closes #5841.
Add pandas cookbook to tutorials (for #5837)
BUG: Bug in selection with missing values via .ix from a duplicate indexed DataFrame failing (GH5835)
Merge pull request #5847 from jseabold/fix-5841

ENH: Improve error message for PeriodIndex to infer_freq. Closes #5841.
Merge pull request #5849 from jreback/dup_selection

BUG: Bug in selection with missing values via .ix from a duplicate indexed DataFrame failing
BUG: fix issue of boolean comparison on empty DataFrames (GH5808)
Merge pull request #5810 from jreback/bool_ops

BUG: fix issue of boolean comparison on empty DataFrames (GH5808)