* Fixed multi-namespace for augmented state which was not covered in 4.2.0.
* The multi-namespace augment state may rearrange the XML namespace attributes.
* Mandatory variables can no longer be deleted.
* This occurs in cases where there are more than one XML namespaces in a config tree, such as `augment`:ed trees.
* Affects all parts of the system, including datastore, backend, restconf and cli.
* Invalid api-path syntax (eg non-matching yang) error changed from 412 operation-failed to 400 Bad request invalid-value, or unknown-element.
* clixon-config YAML file has new revision: 2019-03-05.
* New URN and changed top-level symbol to `clixon-config`
* Removed obsolete `_CLICON_XML_NS_STRICT` variable and `CLICON_XML_NS_STRICT` config option.