BUG: Fix Index.__iadd__ bug by setting equal to __add__

fixes #4996

alias Index's __isub__ to __sub__

document fixes to #4996

index isub test

roll back everything non-iadd related
Add DatetimeIndex and Index documentation.

Start documentation for DatetimeIndex and Index.
 ENH: Ability to tz localize when index is implicility in tz

Fix to issue #4230 which allows to localize an index which is
implicitly in a tz (e.g., reading from a file) by passing infer_dst to
tz_localize.
ENH: Added PySide support for qtpandas.
API: Enable changing the DataFrame in the DataFrameWidget.
DOC: Adding an example of using the DataFrameWidget.
EHN: Allow load_data to load the "Titanic" and other problematic R datasets
TST: Move tests from rpy/common.py to rpy/tests/test_common.py
TST: Add tests to demonstrate the enhancements made to rpy/common.py.
DOC: Add explanation to doc/source/release.rst and doc/source/v0.13.0.txt
BUG: fixed a bug in multi-level indexing with a Timestamp partial indexer (GH4294)
Merge pull request #5088 from jreback/mi_timestamp

BUG: fixed a bug in multi-level indexing with a Timestamp partial indexer (GH4294)
TST: Tests for multi-index construction of an all-nan frame (GH4078)
Merge pull request #5089 from jreback/mi_constructor

TST: Tests for multi-index construction of an all-nan frame (GH4078)
Merge pull request #4706 from rockg/tz-localize-aware

ENH: Ability to tz localize when index is implicility in tz
Merge pull request #5013 from alefnula/qtpandas

ENH: PySide support for qtpandas.
Merge branch 'iadd' of https://github.com/d10genes/pandas into d10genes-iadd

Conflicts:
	doc/source/release.rst
Merge branch 'r-dataset' of https://github.com/unutbu/pandas into unutbu-r-dataset

Conflicts:
	doc/source/release.rst
CLN: Remove internal classes from MultiIndex pickle.

FrozenNDArray had made it into the MI pickle. No reason to do that and
just complicates pickle compat going forward. Now they just output
ndarray instead (which also avoids the unnecessary nested pickle
previously occurring).