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.
Merge branch 'combined'
Added PROFILE=yes cases to test_compile.
Update library directories.