Removed old comment in header to elastic_scatter.
Removed old comment in header to elastic_scatter.

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