Merge remote branch 'origin/feature/7777_run_more_systemtests'
Merge remote-tracking branch 'origin/feature/8042_stitch_many'
Merge remote-tracking branch 'origin/feature/7604_stepscan_system_test'
Merge remote-tracking branch 'origin/feature/7976_replace_flatabs_with_python'
Re #8113. Update PG3Analysis reference result.

It seems that the result changed slightly between my completing #7777 and
it being merged to master.
A tolerance on all the SNSPowderRedux tests is probably a good idea.
Refs #8113 add tolerances
Merge branch 'feature/8113_snspowderredux_small_ref_change' into develop