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

Coerces to object Index instead.
COMPAT: allow string concats to datetimeindex only (int/float are invalid)
DOC: r match function
Update comparison_with_r.rst

rm index
Update comparison_with_r.rst
DOC: fix headers to avoid warnings
DOC: remove usage of code-block in docstrings (#3430)
Merge pull request #5910 from andrewkittredge/master

docstring grammar.
Merge pull request #5903 from jorisvandenbossche/docs-code-snippets

DOC: remove usage of code-block directive in docstrings + fix some warnings
BLD: match version tags when using git-describe to gen version string
Merge pull request #5916 from y-p/PR_setup_git_describe_match_tags

BLD: match version tags when using git-describe to gen version string
BUG: Bug in idxmin/max with object dtypes (GH5914)
Merge pull request #5918 from jreback/index_float

BUG: Bug in idxmin/max with object dtypes (GH5914)
BUG/TST: dt+BDay(n) wrong if n>5, n%5==0 and dt not on offset (GH5890)
DOC: updated release.rst (GH5890)
BLD: remove local autosummary copy
DOC: remove scikits.timeseries dep from faq.rst and docs in general
DOC: update copyright string years
BLD: conf.py fixes
Merge pull request #5911 from dorandeluz/bday-addition

BUG: dt+BDay(n) wrong if n>5, n%5==0 and dt not on offset (GH5890)