BLD: add setup_requires in setup.py so numpy can be used with buildout

Numpy is a setup-time dependency due to some .h files, but is not declared as such. This causes tools like buildout to fail.
TST: Add numexpr arithmetic tests.

Only add 'div' if not python 3

Also checks dtype in test cases for series
ENH: Allow evaluate to pass kwargs to numexpr
BUG: Fix __truediv__ numexpr error

by passing truediv=True to evaluate for __truediv__
and truediv=False for __div__.
BUG: Remove broken frame mod and floordiv str_rep

`%` (modulus) intermittently causes floating point exceptions when used with
numexpr.

`//` (floordiv) is inconsistent between unaccelerated and accelerated
when dividing by zero (unaccelerated produces 0.0000, accelerated
produces `inf`)
TST: Make test_expressions cover more arithmetic operators
BLD: Add useful shortcuts to Makefile

BLD: Add doc task to Makefile
BLD: Make doc not silent

BLD: add tasks to .PHONY

BLD: Only remove *.pyc with make build
Merge pull request #3764 from jtratner/fix_division_with_numexpr

BUG: Fix __truediv__ numexpr error
ENH: enable support for iterator with read_hdf in HDFStore (GH3937)

DOC: update v0.11.1.rst
Merge pull request #3803 from jtratner/makefile-updates

BLD: Add useful shortcuts to Makefile
Merge pull request #3949 from jreback/hdf_iterator

ENH: enable support for iterator with read_hdf in HDFStore (GH3937)
Merge pull request #3903 from ejnens/master

BLD: add setup_requires in setup.py so numpy can be used with buildout
API: more consistency in the to_datetime return types (give string/array of string inputs) (GH3888)
BUG: truncate will only try to convert to dates for an all_dates index
Merge pull request #3890 from jreback/to_datetime

API: (GH3888) more consistency in the to_datetime return types (given string/array of string inputs)
BUG: (GH3925) Indexing with a string with seconds resolution not selecting from a time index
Merge pull request #3931 from jreback/time_indexing

BUG: (GH3925) partial string selection with seconds resolution
DOC add to_datetime to api.rst
WIP some to_datetime docs additions
WIP to_datetime docs more rewriting