expose henry/gcmc results savename. @Surluson I did change root_save_name to gcmc_results_savename since that is more informative. sorry that this will change your code...
changed name of write_unitcell_boundary to write_vtk and fixed bug where filename was not appended with .vtk
make error with FF more informative where it spits out what atom is duplicated
helium params in UFF.csv weren't right so I fixed those.
added geometric rules which UFF calls for.
made mixing rules case insensitive as @Surluson suggested
root_save_nametogcmc_results_savenamesince that is more informative. sorry that this will change your code...write_unitcell_boundarytowrite_vtkand fixed bug where filename was not appended with .vtk