Enhance sample_nuclide to work for total material scatter and fission.
Enhance sample_nuclide to work for total material scatter and fission.

liangjg/openmc,smharper/openmc,bhermanmit/openmc,wbinventor/openmc,johnnyliu27/openmc,samuelshaner/openmc,amandalund/openmc,walshjon/openmc,wbinventor/openmc,amandalund/openmc,smharper/openmc,paulromano/openmc,shikhar413/openmc,lilulu/openmc,smharper/openmc,smharper/openmc,mit-crpg/openmc,kellyrowland/openmc,nhorelik/openmc,shenqicang/openmc,mit-crpg/openmc,paulromano/openmc,amandalund/openmc,lilulu/openmc,liangjg/openmc,johnnyliu27/openmc,wbinventor/openmc,mjlong/openmc,walshjon/openmc,lilulu/openmc,samuelshaner/openmc,mit-crpg/openmc,nhorelik/openmc,kellyrowland/openmc,shikhar413/openmc,bhermanmit/cdash,sxds/opemmc,sxds/opemmc,amandalund/openmc,samuelshaner/openmc,shikhar413/openmc,wbinventor/openmc,shenqicang/openmc,walshjon/openmc,paulromano/openmc,paulromano/openmc,mjlong/openmc,samuelshaner/openmc,johnnyliu27/openmc,liangjg/openmc,johnnyliu27/openmc,walshjon/openmc,mit-crpg/openmc,bhermanmit/openmc,liangjg/openmc,shikhar413/openmc