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
ENH: assert_X_equal with check_less_precise should apply to index/columns too
BLD: move perf_HEAD functionality into test_perf. -H arg
BLD: fix path handling in test_perf
BLD: test_perf will read BUILD_CACHE_DIR from .build_cache_dir if it exists
BLD: test_perf, add -n, number of vb runs to average results over
BLD: test_perf, add -N, run HEAD vbenchmarks multiple times seperately
BUG: PeriodIndex.tolist boxes to list of Periods #3178
BUG: PeriodIndex.get_loc KeyError now reports Period instead of ordinal #3179
CLN: pass in Period instead of Period repr to remove extra double quotes #3179
TST: DataFrame.to_records(index=True) doesn't work with MultiIndex GH3189
Merge pull request #3173 from y-p/less_precise

ENH: assert_X_equal with check_less_precise should apply to index/cols too
TST: bring back disabled tests in test_to_csv_moar after GH3173
BUG: DataFrame.to_records(index=True) doesn't work with MultiIndex GH3189

closes #3189
Merge branch 'GH3189'

* GH3189:
  BUG: DataFrame.to_records(index=True) doesn't work with MultiIndex GH3189
  TST: DataFrame.to_records(index=True) doesn't work with MultiIndex GH3189
DOC: update RELEASE.rst
DOC: various editing
TST: fix broken test case on py3 and add assertRaises #3179