RF - fixed bug found in dti.py and added LS function...some attributes in tensor class were optimized
RF - fixed bug found in dti.py and added LS function...some attributes in tensor class were optimized

nilgoyyou/dipy,oesteban/dipy,JohnGriffiths/dipy,oesteban/dipy,villalonreina/dipy,jyeatman/dipy,JohnGriffiths/dipy,matthieudumont/dipy,maurozucchelli/dipy,maurozucchelli/dipy,samuelstjean/dipy,samuelstjean/dipy,matthieudumont/dipy,samuelstjean/dipy,rfdougherty/dipy,nilgoyyou/dipy,beni55/dipy,FrancoisRheaultUS/dipy,StongeEtienne/dipy,StongeEtienne/dipy,sinkpoint/dipy,mdesco/dipy,jyeatman/dipy,Messaoud-Boudjada/dipy,demianw/dipy,mdesco/dipy,demianw/dipy,FrancoisRheaultUS/dipy,Messaoud-Boudjada/dipy,villalonreina/dipy,maurozucchelli/dipy,rfdougherty/dipy,beni55/dipy,sinkpoint/dipy