* Made NETCONF message handling more strict according to RFC 6241
* Set `CLICON_NETCONF_MESSAGE_ID_OPTIONAL` to true to accept omission of message-id attribute
* Fixed: [need make sure message-id exist in rpc validate #240](https://github.com/clicon/clixon/issues/240)
* This enables that RPOC handles can call commit and validate via lib
* The commit/validate API is now: `candidate_validate()` and `candidate_commit()`
* clixon_restconf daemon is installed in /usr/local/sbin (as clixon_backend), instead of /www-data
* `configure --with-wwwdir=<dir>` remains but only applies to fcgi socket and log
* New option `CLICON_RESTCONF_INSTALL_DIR` is set to where clixon_restconf is installed, with default `/usr/local/sbin/`
* Restconf drop privileges user is defined by `CLICON_RESTCONF_USER`
* `configure --with-wwwuser=<user>` is removed
* clixon_restconf drop of privileges is defined by `CLICON_RESTCONF_PRIVILEGES` option
* New clixon-restconf@2020-05-20.yang revision
* Added: restconf `log-destination`
This include plugin module init and exit functions
New type: clixon_plugin_t exposed via public API while struct clixon_plugin is private
- Makefile changes for static linkage using "LINKAGE=static"
- Moved nacm external init to later stage in backend_main
* This means that files and datastores supporting modstate also looks for deleted or updated yang modules.
* A stricter binding which gives error if loading outdated YANG file does not exist.
* Stricter yang checks: you cannot do get-config on datastores that have obsolete YANG
* Added xerr output parameter to `xmldb_get0()`
- Stricter CLICON_BACKEND_RESTCONF_PROCESS :
- if set, restconf daemon queries backend for its config
- if not set, restconf daemon reads its config from main config file
* Replaces the hardcoded "config" keyword.
* Implemented by a compile-time option called `DATASTORE_TOP_SYMBOL` option in clixon_custom.h
* Tests: added endtest to all tests. Removed all premature exits if BE=0
* Introduced a delay before making process start/stop/restart processes for race conditions when configuring eg restconf
* For restconf `CLICON_BACKEND_RESTCONF_PROCESS`, restart restconf if restconf is edited.
* Fixed: [Augment that reference a submodule as target node fails #178](https://github.com/clicon/clixon/issues/178)
* Fixed a memory error that was reported in slack by Pawel Maslanka
* The crash printout was: `realloc(): invalid next size Aborted`
* Not backward compatible: All uses of the ca-auth callback in restconf plugins must be changed
* New version is: `int ca_auth(h, req, auth_type, authp, userp)`
* where `auth_type` is the requested authentication-type (none, client-cert or user-defined)
* `authp` is the returned authentication flag
* `userp` is the returned associated authenticated user
* and the return value is three-valued: -1: Error, 0: ignored, 1: OK
* For more info see [clixon-docs](https://clixon-docs.readthedocs.io/en/latest/restconf.html)
* New clixon-restconf@2020-12-30.yang revision
