barcharts.py: add zIndexOverrides attribute
barcharts.py: add zIndexOverrides attribute

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