blur volumetric lights


git-svn-id: svn://svn.tuxfamily.org/svnroot/tesseract/main@1732 b412e182-2ed4-4078-95c4-27dc59f57fa9
volumetric light shader fixes


git-svn-id: svn://svn.tuxfamily.org/svnroot/tesseract/main@1733 b412e182-2ed4-4078-95c4-27dc59f57fa9