CLN: simplify series plotting
BUG: Groupby.get_group doesnt work with TimeGrouper
CLN: remove items/ref_items attributes from Block class

Now, there's one authoritative mapping from BlockManager axis0 to
axis0 of subordinate blocks:

* _blknos[loc] is block number where loc-th item resides
* _blklocs[loc] is location in given block of loc-th item

Blocks support this mapping with blk._ref_locs attributes that
enumerate all items contained in that block.
CLN: rename Block.ref_locs -> mgr_locs to reduce confusion

PERF: add BlockPlacement class to optimize range-like cases

CLN: unify get_slice & take/reindex ops along axis0

TST: add slicing/taking/reindexing tests for BlockManagers

CLN: remove unused code
BLD: numpy 1.9-dev requires cython for installation
Merge pull request #6745 from immerrr/refactor-blockmanager

CLN: revisit & simplify Block/BlockManager, remove axes
Force 64-bit integers to comply with cython buffer specs
COMPAT:  32-bit platform compat for Panel.count
ENH: pivot_table can now accept Grouper
Merge pull request #6913 from sinhrks/pivotg

ENH: pivot_table can now accept Grouper
Boxplot by quartile example code

Add mpl_style option as cookbook currently doesn't have plots
COMPAT: change neg of boolean to inv (deprecation in numpy 1.9)
COMPAT: remove deprecation warnings on __new__ (in computation/pytables)
COMPAT: windows dtype fix in for Panel.count
Merge pull request #6981 from pydata/winfix

COMPAT: windows dtype fix in for Panel.count
TST: windows dtype fix for test_pivot (GH6913)
COMPAT: fix array_to_datetime on comparison of NaT
COMPAT: fix warning for slice indexers when using floats in iloc that are convertible
Merge pull request #6960 from jreback/warnings

COMPAT: fix numpy 1.9-dev deprecation warnings in test suite
TST: test_frame/test_sum not comparing correctly on smaller sized dtypes (GH6982)
COMPAT: remove deprecated options from printing in test suite (GH6984)