New classes MemberValidator and InstanceValidator for expressibly validating instances of classes in source code.
Validation Attributes can now have associated error messages.
Various improvements.
Breaking changes from previous version:
IValidator is renamed to IValueValidator and a new IValidator is introduced.
InvalidRuleException and ValidationOffense classes change namespace.
ValidationOffense.Rule changes to a string and is renamed to ValidationOffense.OffendedRule.
Interface IObjectValueRule becomes obsolete and replaced by a new class AttributeRule.
NotWhiteSpaceAttribute class is renamed to NotNullOrWhiteSpaceAttribute.
More accurate handling of null strings in Attribute validations.
Some string based decorators are more tolerant to null strings and do not throw ArgumentNullException.