Implement Retrieve/UpdateBinContent (fix ROOT-6981)
Protect GetBinContent/SetBinContent for not valid bin numbers
Fix TH2Poly destructor (see http://root.cern.ch/phpBB3/viewtopic.php?f=3&t=19060)
Fix Th2Poly::AddBin(x1,x2,y1,y2) by closing the graph
Fix TH2Poly::Fill for entries in the sea