Migrating to Wicket 6.0

Environment

• Wicket 6.0 requires at least Java 6

Form Processing

Validation

• `DateValidator` no longer has static factory methods, use `new DateValidator(min,max)` instead
• `StringValidator` no longer has static factory methods, use `new StringValidator(min, max)` instead
• `StringValidator` will add the `maxlen` attribute if added to a component attached to an input tag
• `AbstractValidator` has been removed
• Most validators provide a `decorate(ValidationError, Validatable)` method for overriding how they report errors

... more to come ...