BLD: make affinity optional, and reduce user message drama
BUG/BLD: pytables version checking was incorrect
BLD: test_perf.py, add --base-pickle --target-pickle options to test_perf
Merge pull request #3734 from y-p/PR_test_perf_pickle_compare

 BLD: test_perf.py, add --base-pickle --target-pickle options to test_perf
CLN: remove spurious print
Merge pull request #3735 from cpcloud/fix-travis-bug

BUG/BLD: pytables version checking was incorrect
PERF: (GH3733) where block splitting now done in at most 2 blocks rather than

      item-by-item; add vb_suite tests for masking
BUG: _interleave now returns an lcd of int64 or 2 x the intsize if

     uints are seen