Added comments for new subroutines in tally module.
Added comments for new subroutines in tally module.

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