Revision 410

(Classification):
        Uses the new ClassData* classes. Modification messages are
        passed up to the parent layer (if it exists).
(ClassData): New class to encapsulate the common data in each
        classification property.
(ClassDataDefault): Represents the Default class. data.
(ClassDataPoint): Represents a single class. data point
(ClassDataRange): Represents a class. range
(ClassDataMap): Represents a class. map (unused).