TST: fix date parsing issue in test_frame/test_replace_datetime
WIP: Index no longer an ndarray sub-class (GH5080)
CLN: add searchsorted to core/base (GH6712, GH7447, GH6469)
hopefully fix identity
fixup tests in test_timeseries for reverse ndarray/datetimeindex comparisons
fix algos / multi-index repeat (essentially this is a bug-fix)