QRDecomposition: fix stupid bug affecting mass constraints for k-factors


git-svn-id: svn+ssh://svn.cern.ch/reps/lhcb/Urania/trunk/PhysFit/B2DXFitters@167422 4525493e-7705-40b1-a816-d608a930855b
DecayTreeTupleSucksFitter: adapt to double precision tuples


git-svn-id: svn+ssh://svn.cern.ch/reps/lhcb/Urania/trunk/PhysFit/B2DXFitters@167431 4525493e-7705-40b1-a816-d608a930855b