took care of python3 floating point division issue with tile_factor in filter.py
took care of python3 floating point division issue with tile_factor in filter.py

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