From Philippe;

This patch adds support in the new tree cloning scheme for
        TTree *clone = chain->GetTree()->CloneTree(0);
If chain is really a TChain, need to make sure that it keeps track of the clones even when the tree that was
actually cloned is deleted by LoadTree.


git-svn-id: http://root.cern.ch/svn/root/trunk@6848 27541ba8-7e3a-0410-8455-c3a389f83636