add tensor fit to mapmri
add tensor fit to mapmri

nilgoyyou/dipy,villalonreina/dipy,matthieudumont/dipy,StongeEtienne/dipy,demianw/dipy,JohnGriffiths/dipy,JohnGriffiths/dipy,FrancoisRheaultUS/dipy,StongeEtienne/dipy,villalonreina/dipy,nilgoyyou/dipy,FrancoisRheaultUS/dipy,matthieudumont/dipy,demianw/dipy