Fix old surface source reading on settings
Fix old surface source reading on settings

walshjon/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,shikhar413/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,amandalund/openmc,shikhar413/openmc,walshjon/openmc,amandalund/openmc