Making mesh lines some minimal width.
Making mesh lines some minimal width.

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