The `xmldb_put` is failing due to the `x_spec` field not being set on the xml tree (`xt`) due to no yang spec being passed to the `clixon_xml_parse_string` function.
* Added new revision of main example yang: `clixon-example@2020-12-01.yang`
* Fixed [YANG: key statement in rpc/notification list #148](https://github.com/clicon/clixon/issues/148)
* Do not check uniqueness among lists without keys
* The existing autocli does not support modes, complete paths must be given, eg: `set a b c d 42`.
* In the new auto-cli, automatic modes are present at each YANG syntax node level, eg the above can be given as: `edit a b c; set d 4; top`
* The existing CLI API remains, the new API is as follows: `cli_auto_edit()`, `cli_auto_up()`, `cli_auto_top()`, `cli_auto_show()`, `cli_auto_set()`, `cli_auto_merge()`, `cli_auto_create()`, `cli_auto_del()`.
* See `test/test_cli_auto.sh` for an example of the new API, and `apps/cli/cli_auto.c` for the source code of the new callback API.
* Documentation will be appear and full integration with the main example.
* Added inline state field to clixon-example.yang
* Added new clicon_data_cvec_*() API for generic cvec structs
* Only requests on the form: `<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><edit-config>...` will be accepted
* All replies will be on the form: `<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">...`
* Requests such as: `<rpc><edit-config>...` will not be accepted.
* You can revert this behaviour (to clixon pre-4.6 behaviour) by enabling `CLICON_NAMESPACE_NETCONF_DEFAULT`
* This API change is a consequence of: [copy-config's RPC cxobj parameter does not contain namespace #131](https://github.com/clicon/clixon/issues/131)
* In summary, a user registers an upgrade callback per module. The callback is called at startup if the module is added, has been removed or if the revision on file is different from the one in the system.
* The register function has removed `from` and `rev` parameters: `upgrade_callback_register(h, cb, namespace, arg)`
* The callback function has a new `op` parameter with possible values: `XML_FLAG_ADD`, `XML_FLAG_CHANGE` or `XML_FLAG_CHANGE`: `clicon_upgrade_cb(h, xn, ns, op, from, to, arg, cbret)`
* Reduced memory for attribute and body objects, see `XML_NEW_DIFFERENTIATE` compile-time option.
* Optimized cbuf handling in parsing and xml2cbuf functions.
* Optimized xml scanner to read strings rather than single chars
* Optimized xml_merge for the case of disjunct trees.
* Added: stats RPC for clixon XML and memory statistics.
* Added: restart-plugin RPC for restarting individual plugins without restarting backend.
* xml-stats moved from clixon-config.yang as state data to an rpc `datastats` in clixon-lib.yang
* Experimental: restart_plugin
* Two new plugin callbacks added
* ca_daemon: Called just after a server has "daemonized", ie put in background.
* ca_trans_commit_done: Called when all plugin commits have been done.
* Note: If you have used "end" callback and usign transaction data, you should probably use this instead.
* Two new plugin callbacks added
* ca_daemon: Called just after a server has "daemonized", ie put in background.
* ca_trans_commit_done: Called when all plugin commits have been done.
* `clixon_netconf_error(category, xerr, msg, arg)` removed first argument -> `clixon_netconf_error(xerr, msg, arg)`
* Renamed utility function `clixon_util_insert()` to `clixon_util_xml_mod()` and added merge functionality.
* Fixed: Insertion of subtree leaf nodes were not made in the crrect place, always ended up last regardless of yang spec (if ordered-by system).
* `clixon_xml_parse_string()`
* `clixon_xml_parse_file()`
* New JSON parsing API, with same signature as XML parsing:
* `clixon_json_parse_string()`
* `clixon_xml_parse_file()`
* XML YANG binding API have been rearranged as follows:
* `xml_bind_yang_rpc()`
* `xml_bind_yang_rpc_reply()`
* `xml_bind_yang()`
* `xml_bind_yang0()`
* If fails, exit with error message, eg: `Yang error: Sanity check failed: LIST vsDataContainer lacks key statement which MUST be present (See RFC 7950 Sec 7.8.2)`
* Can be disabled by setting `CLICON_CLICON_YANG_LIST_CHECK` to `false`
