fix for bug https://sft.its.cern.ch/jira/browse/ROOT-4893

 the content of the list fListOfClasses was not deleted  in the constructor of TDataBasePDG


git-svn-id: https://root.cern.ch/svn/root/trunk@49275 27541ba8-7e3a-0410-8455-c3a389f83636
- Add icons for several types of objects (canvas, histo, graph, ...)
- Adjust bin size (was fixed size) for TH2 drawn in 3D (lego)


git-svn-id: https://root.cern.ch/svn/root/trunk@49277 27541ba8-7e3a-0410-8455-c3a389f83636