Revised annotations: moved Widget#headIsDummy to Required#otherThanHead, moved Widget#atLeast to Required#atLeast, added value to PastDate and removed reference to the DatePattern, and added comments.
Updated README: moved Widget#atLeast to Required#atLeast.
Revised Validator interface to customize it and test it easily: removed java.lang.reflect.Field from the arguments of the Validator, added related annotation and FieldData instead of the java.lang.reflect.Field.