OWFeatureConstructor: Use Values in expression
OWFeatureConstructor: Use Values in expression

Enable using values instead of values indices when writting expression for new discrete feature.

cheral/orange3,cheral/orange3,cheral/orange3,cheral/orange3,marinkaz/orange3,qPCR4vir/orange3,marinkaz/orange3,kwikadi/orange3,kwikadi/orange3,qPCR4vir/orange3,qPCR4vir/orange3,cheral/orange3,cheral/orange3,qPCR4vir/orange3,marinkaz/orange3,marinkaz/orange3,qPCR4vir/orange3,qPCR4vir/orange3,kwikadi/orange3,kwikadi/orange3,marinkaz/orange3,marinkaz/orange3,kwikadi/orange3,kwikadi/orange3