implementing best far and multiple nevent, livetime changes to py3 spiir version
This branch implements best far feature from py2 spiir to py3 spiir and also adds the multiple nevent and livetime. See !195 (merged) and !176 (merged).
This branch implements best far feature from py2 spiir to py3 spiir and also adds the multiple nevent and livetime. See !195 (merged) and !176 (merged).