Avoided NaNs in keff and fission analog tallies when micro_xs(i)%absorption was zero as it is for He-4.
Fixed nu-scatter (w/ energyout filter) survival biasing issue.
Merge remote-tracking branch 'origin/develop' into survival
Fixed erroneous tallying of fission and kappa-fission in cases without survival biasing.
Fixed flux tallying for case of survival biasing.
Merge remote-tracking branch 'upstream/develop' into survival
Merge remote-tracking branch 'upstream/develop' into survival
Moved scattering to occur before russian roulette, and set last_wgt to 0 as well when a particle is killed via russian roulette.
Updating survival to incorporate harmonics branch.
Fixed a merge conflict issue.
Updated survival biasing test results.
Updating test score fission results based on survival biasing updates.
Merge pull request #287 from nelsonag/survival

Fixed erroneous results from survival biasing (try #2)