Removed AgaviValidationArgumentResult and AgaviValidationValidatorResult and associated APIs.
Changed AgaviValidationReport::getResult() to return null if no result code exists at all (= no validators defined), and adjusted AgaviValidationManager::getReport() to remain backwards compatible (continues to return NOT_PROCESSED in this case)
Fixed AgaviReport::addIncident()
Fixed AgaviReport::getAuthoritativeArgumentSeverity()
Adjusted FPF to use new API.
Cleaned up docs
Refs #939