Merge pull request #7544 from sinhrks/dtmixin

BUG: DatetimeIndex.asobject raises ValueError when contains NaT
PERF: vbench for mixed groupby with datetime (GH7555)

PERF: perform coercing and casting on groupby agg by blocks
Merge pull request #7085 from michaelaye/add_notimp_error

adding a NotImplementedError for simultaneous use of nrows and chunksize...
Merge pull request #7560 from jreback/groupby_first_perf

PERF: vbench for mixed groupby with datetime (GH7555)
API: add/clarify numpy ufunc prepare/wrap
Remove unused variable assignment
Add notes deprecating in_ipnb and in_qtconsole
Merge pull request #7499 from takluyver/ipy-no-detect-frontend

Deprecate detection of IPython frontends
DOC: Add cookbook recipe like R's `expand.grid()`

Add `expand_grid()` recipe to cookbook

Add note about cookbook recipe to release notes

Revert "Add note about cookbook recipe to release notes"

This reverts commit e431a024c2e688f9917cafb12235ee72ecc3e119.

Remove pandas import, print dataframe in cookbook
DOC: Fix parameter in reindex_axis docstring
Merge pull request #7556 from onesandzeroes/expand-grid

DOC: Cookbook recipe for emulating R's expand.grid() (#7426)
BUG/PERF: perf issues in object groupby aggregations (GH7555)
Merge pull request #7568 from jreback/perf2

BUG/PERF: perf issues in object groupby aggregations (GH7555)
TST: Remove else after except in tests for io.data.Options.

Made the old tests consistent with the new tests, also passed the RemoteDataError on skip.

CLN:  Moved test for no tables to the get_option_tables method.
Merge pull request #7564 from dstephens99/master

TST: Remove else after except in tests for io.data.Options.
Merge pull request #7547 from toddrjen/nanopsclean

Minor cleanups for nanops
SQL: don't reflect full database GH7396
Redesigned pandas.io.gbq to remove bq.py as a dependency for everything except unit testing. Minor API changes were also introduced.
BUG: bug in float64index assignment with a non scalar indexer
Squashed commit of the following:

commit 5e9e0fa29d727953583a116638a9d0db81f9ed21
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 19:53:35 2014 -0400

    Fixed issue with empty lines

commit 57b54918b251ab77f000b575d77bcce3affcb27a
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 16:31:27 2014 -0400

    Added reference to new functionality in docs

commit a2371638691584416439d3c6a4dd2ef1829dcbe3
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 16:26:06 2014 -0400

    Implemented functionality to ignore comment lines, wrote a test