TST: add test for DataReader class and fix failing network tests for good
Merge pull request #4054 from cpcloud/fix-failing-data-py-tests

TST/BUG: fix failing data.py tests for good
TST/BUG: do not call regular density tests when testing kde color
BUG: deal with gcf-style figures in hist_series
PERF: optimize iloc for unique case
Merge pull request #4021 from cpcloud/hist-figure-arg-fix

BUG: allow series to use gcf-style figures
Merge pull request #4070 from jreback/iloc_perf

PERF: optimize iloc for unique case