Add colors and filename argument to Universe.plot
Add colors and filename argument to Universe.plot

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