Add xyz default for openmc.stats.Point constructor
Add xyz default for openmc.stats.Point constructor

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