Fix constrained fit option
Fix constrained fit option

SasView/sasview,lewisodriscoll/sasview,lewisodriscoll/sasview,SasView/sasview,SasView/sasview,lewisodriscoll/sasview,lewisodriscoll/sasview,SasView/sasview,SasView/sasview,lewisodriscoll/sasview,SasView/sasview