piecharts.py: fix checkLabelOverlap for 3d pie
piecharts.py: fix checkLabelOverlap for 3d pie

kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,kanarelo/reportlab,Distrotech/reportlab,Distrotech/reportlab,kanarelo/reportlab,Distrotech/reportlab,Distrotech/reportlab,kanarelo/reportlab