Fix bug in autodetermining root universe (didn't account for lattice outer)
Fix bug in autodetermining root universe (didn't account for lattice outer)

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