Ability to tally flux with individual nuclides (even though it doesn't make sense). Closes #117 on github.
Do not allow user to use surface filter since it's not implemented.
Added analog and implicit absorption estimator of k-effective.
Move printing of k-effective to separate subroutine.
Implemented combined estimator for k-effective.
Consistently order collision, absorption, tracklength.
Simplify permutations in calculate_combined_keff.
Add confidence interval for combined keff estimator.
Moved calculation of combined keff before tally_statistics.
Move calculate_combined_keff to eigenvalue module.
Make sure n_realizations is at least 4 for combined keff calculation.
Added combined estimate of k-effective to state point.
Add/fix two checks for outgoing energy filters. Closes #149 on github.
Remove unused explicit imports.
Fix a few gfortran debug warnings.
Merge branch 'combined'
Added PROFILE=yes cases to test_compile.
Update library directories.
Check for invalid tally filter.
Updated release notes for 0.5.1.