Update summary file format changing surfaces -> region
Update summary file format changing surfaces -> region

smharper/openmc,liangjg/openmc,johnnyliu27/openmc,johnnyliu27/openmc,amandalund/openmc,liangjg/openmc,shikhar413/openmc,bhermanmit/openmc,walshjon/openmc,mit-crpg/openmc,samuelshaner/openmc,mit-crpg/openmc,smharper/openmc,mjlong/openmc,shikhar413/openmc,amandalund/openmc,bhermanmit/openmc,liangjg/openmc,paulromano/openmc,paulromano/openmc,johnnyliu27/openmc,wbinventor/openmc,liangjg/openmc,amandalund/openmc,johnnyliu27/openmc,samuelshaner/openmc,mjlong/openmc,smharper/openmc,walshjon/openmc,wbinventor/openmc,mit-crpg/openmc,smharper/openmc,walshjon/openmc,amandalund/openmc,shikhar413/openmc,paulromano/openmc,kellyrowland/openmc,wbinventor/openmc,samuelshaner/openmc,walshjon/openmc,wbinventor/openmc,mit-crpg/openmc,samuelshaner/openmc,kellyrowland/openmc,paulromano/openmc,shikhar413/openmc