add comparisons operator to the Period object and fixes issue 2781
move the Period tests in test_period.py and add assertRaises tests for comparisons
use a function factory for comparisons of Period objects
Resample docstring default values changed

This docstring seems better, since TimeGrouper specifies it [that way][1] too:

[1]: https://github.com/pydata/pandas/blob/master/pandas/tseries/resample.py#L27
Remove confusing default val hints from docstrings
TST: test for GH2623, object in frame upconverting a datetime64[ns] in another column
BUG: GH2817, raise the correct KeyError that the multi-index is not sorted
BUG: HDFStore bug when appending to a table, .typ not recreated on 2nd appends
      when min_itemsize is specified it caused an Exception
BUG: GH2719, fixed reshape on a Series with invalid input
Merge pull request #3126 from jreback/hdf_bug

BUG: HDFStore bug when appending to a table, .typ not recreated on subsequent appends
Merge pull request #3127 from jreback/reshape

BUG: GH2719, fixed reshape on a Series with invalid input
DOC: add example and warning on fallback indexing for float indexes.
BUG: fix cython caching in setup.py
BUG: fix NameError issue in GH2787
Merge pull request #3135 from jreback/GH2787

BUG: fix NameError issue in GH2787
ENH: added selection to an unordered timeseries the same semantics as an ordered timeseries (GH2437)
Merge pull request #3136 from jreback/GH2437_2

ENH: GH2437 added selection to an unordered timeseries
ENH: GH3070, extend slicing semantics for datelike indexed DataFrames with a string to work like
     TimeSeries (e.g. df['2001'] works)
DOC: cookbook examples
CLN: cleanup arguments in generate_code.py