From Philippe:

This patch insures that TTreeFormula only call GetEntry once per branch
per entry (This speeds up evaluating formula where the same branch is use
several times).

Update TTreeIndex (and hence TTree::BuildIndex) to be able to
work correctly independently of the state of the TTree object (It previously
__required__ TTree::fReadEntry to be equal to -1).

Make TTreeIndex::Print platform independent (it was not
printing correctly on windows).


git-svn-id: http://root.cern.ch/svn/root/trunk@11046 27541ba8-7e3a-0410-8455-c3a389f83636