Revision 1433

(ClassGrid.CreateTable): Add fieldType parameter.
(ClassTable.Reset): Add fieldType parameter and use it, rather
        than asking the classification.
(Classifier.__init__): Remember the original class's field
        and ask the layer for the field type, rather than the classification.
(Classifier.__SetGridTable): Retrieve the field and field type
        for the table because they are not in the classification.
(Classifier._OnTry, Classifier._OnRevert): Set the classification
        field on the layer in addition to the classification itself.