* Closer adherence to RFC 7950. Some of this is changed behavior, some is new feature.
* Essentially instead of looking at the referring leaf, context is referred(target) node
* Validation uses referred node
* Validation changed to use type of referred node, instead of just "string"
* Auto-cli
* Changed to use type of referred node for typecheck
* Completion uses referred node
* Required instance / less strict validation
* New: Leafrefs must refer to existing data leaf ONLY IF YANG `required-instance` is true
* Previous: All leafrefs must refer to existing data leaf node
* Fixed: [Autocli does not offer completions for leafref to identityref #254](https://github.com/clicon/clixon/issues/254)
