TST: test_diagnostic, add results with pandas, see issue #962
TST/STY delint 2 test modules (pylint false errors and warnings)
TST/STY stats.tests ignore/remove some pylint errors and warnings
TST/STY test_ar, test_arima changes to remove pylint errors (red)
BUG ttest_power avoid endless loop in scipy.special nct closes #1011
BUG: fix some pylint errors and noise, fix examples (refactoring victims)
BUG: fix incorrect fix for ttest_power closes #1011
Merge pull request #997 from josef-pkt/misc_13

TST/BUG: Bug fixes and tests for diagnostic and pylint fixes.