Add new evaporation spectrum sampling method outlined in LA-UR-14-27694. Still
need documentation.
Update documentation for evaporation spectrum.
Fix problem with -t, --track command-line flag.
Added support for plot level depth, removed id from filename
Updated documentation
Fixed plot filename issue
Allow cells with no surfaces.
Updated docs for cells with no surfaces
Change !$omp critical directives to !$omp atomic where possible.
Fixed typo for #341
Make global_tallies allocatable instead of automatic.
Merge pull request #341 from smharper/no_surfaces

Ability to model cells with no surfaces
Merge pull request #340 from nhorelik/plot_level

Support for plotting cells/mats on middle universe levels
Fix typo from last merge.
Merge branch 'develop' into atomic
Merge pull request #342 from paulromano/atomic

Use OpenMP atomic updates instead of critical sections
Mention CMake in quick install instructions.
Merge pull request #337 from paulromano/evaporation

Improved evaporation spectrum sampling algorithm
Merge branch 'develop' into log-energy-grid
Make number of bins for log grid adjustable by user.