Applied patch by Terna S.p.A. to hide null values on the chart (not more forced to 0)

git-svn-id: svn://svn.forge.objectweb.org/svnroot/spagobi/V_4.x/Server/trunk@21635 99afaf0d-6903-0410-885a-c66a8bbb5f81


git-svn-id: svn://svn.forge.objectweb.org/svnroot/spagobi/V_4.x/Server/trunk@21636 99afaf0d-6903-0410-885a-c66a8bbb5f81


git-svn-id: svn://svn.forge.objectweb.org/svnroot/spagobi/V_4.x/Server/trunk@21638 99afaf0d-6903-0410-885a-c66a8bbb5f81