Merge topic 'SIMPLEITK-505_AddThreadholdMeasurement'

e4a385af Adding Threshold measurement results for histogram based filters
Merge topic 'SIMPLEITK-500_AddAdditionalDocsToPythonPackages'

e0a8cb35 BUG: Adding missing additional docs as data_file in python setup
Merge branch 'master' into next

Change-Id: I4fdc5b175f507a09690aa78b8eb03c5963dea9a4