Validation was added for the various data object according to the OPC UA Specification. There was some rework of inheritance of the different classes. Proper addition of UAEURange, UARange, UAExtensionObject, UAEngineeringUnits, UAEUInformation, and UAVariants (amoung others). Additionally, parsing and tests were updated to reflect the new changes.
The json_encoding method was implemented for most of the classes.