import dev branch (up to rev. 24397)

- merge implementation from David of TH2::ProjectionX and TH2::ProjectionY in a common method 
- fix a coubple of bugs in projections of TH3 found thanks to the new projection test from David
- improve KolmogorvSmirnov test in 2D and 3D. Make it also working for weighted histograms. 
  For the 3D tests use as probing max distance the one obtained using all possible axis combination for the order. 
  It is arbitrary (as in the 2D case), but at least consistent. A better method, like the one proposed by Peacock, 
  should be used for the multi-dim KS test. 
- add some extra comments for projections of profiles to histograms using option "W". Fix also an un-wanted 
  extra calls to Sumw2()


git-svn-id: http://root.cern.ch/svn/root/trunk@24415 27541ba8-7e3a-0410-8455-c3a389f83636