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.
Check for invalid tally filter.
Updated release notes for 0.5.1.
Incremented version number to 0.5.1.
Updated year in output module.
Fixed error in reading state point in parallel.
Add tallies.xml to test_statepoint_restart.
Updated copyright year in man page.
Fixed bug in statepoint.py for multiple generations per batch.
Fixed statepoint spec in documentation.