Make batches/interval sub-attribute optional in settings.rnc.
Make batches/interval sub-attribute optional in settings.rnc.

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