added support for selecting multiple nth values
adjust timezone when adding date offsets for DST. fixes #5175
PERF: StataReader is slow

StataReader does not make use of vectorized operations.

To improve performance, the following changes have been made:

* Use numpy.frombuffer to real the stored data in a single operation
* Vectorize date conversion
* Removal of unreachable private functions

A test was added to verify the conversion of dates that are out of the range
supported by datetime64[ns]
Merge pull request #8073 from bashtage/stata-read-batching

PERF: StataReader is slow
TST: platform indexing, xref GH8007
BUG: rolling_count() and expanding_*() with zero-length args; rolling/expanding_apply() with min_periods=0
CLN: PEP8 cleanup of holiday.py
PERF: StataWriter is slow

StataWriter wrote data using scalar operations.  This has been replaced using
numpy's internal binary writer (tofile).

Changes needed to improve performance include:

* Vectorized pandas date to Stata date conversion
* Vectorized null padding
* Conversion of string columns to fixed width numpy string arrays
* Conversion to record array
Merge pull request #8079 from bashtage/stata-write-performance

PERF: StataWriter is slow
TST: TestYahooOptions issue
ENH: add support dtype='category' in Series constructor
BUG: fix reindexing to an all-nan Categorical (GH8076)
Merge pull request #8075 from jreback/cat2

ENH: add support dtype='category' in Series constructor
Added chunksize argument to to_sql

Adding chunksize parameter in to_sql method of DataFrame

Fix Travis CI failures

Changing transaction management to be compatible with SQLAlchemy 0.7.1

Code review fixes

Documentation updates

Documentation fixes

Fixes
BUG: left join on index with multiple matches (GH5391)
Merge pull request #8062 from artemyk/to_sql_chunksize

Added chunksize argument to to_sql
BUG: fix checking of table name in read_sql (GH7826)
Merge pull request #7961 from jorisvandenbossche/sql-7826

BUG: fix checking of table name in read_sql (GH7826)
ENH: add support for datetime.date/time in to_sql (GH6932)
Merge pull request #8085 from mortada/pep8_cleanup

CLN: PEP8 cleanup of holiday.py