In the handling of forms, the way the values of the multivalued parameters are encoded into a single string is duplicated in several places, both in the Form mechanism and in the code using the forms. The goal here is to abstract this encoding in a single place (GenericFieldTemplate) and by using the FieldValuesTemplate and FieldValue new classes. Therefore, additonnally to abstract the way the values are encoded, the possible field values are then also reified into tthe FieldValuesTemplate class and each of them reified by the FieldValue class. These classes allow to to handle objets instead of dictionnary (map of key -> value aka field value id -> field value localized value).
