New API is as follows:
* `clixon_xml2file()` - Print internal tree as XML to file
* `clixon_xml2cbuf()` - Print internal tree as XML to buffer
* `clixon_json2file()` - Print internal tree as JSON to file
* `clixon_json2cbuf()` - Print internal tree as JSON to buffer
* `clixon_cli2file()` - Print internal tree as CLI format to file
* `clixon_txt2file()` - Print internal tree as text format to file
* Added `skiptop` parameter, if set only apply to children of a node, skip top node
* default is 0
* Functions are merged, ie removed and replaced with more generic functions
* `xml2json_cbuf()`: Added `skiptop` parameter: `xml2json_cbuf(..., int skiptop)`
* `xml2json()` and `xml2json_cb()` merged into `xml2json_file()` with `skiptop`
* Replace `xml2json(...)` with `xml2json_file(..., stdout, 0)`
* Replace `xml2json_cb(...)` with `xml2json_file(..., 0)`
* `clicon_xml2cbuf()`: Added `skiptop` parameter: `clicon_xml2cbuf(..., int skiptop)`
* `xml2cli()`: Added `skiptop` parameter: `xml2cli(..., int skiptop)`
- Changed logic on how to find clixon_restconf in pseudo plugin
- Removed ==== in constants to avoid conflict with git merge
- Remove assert
- Added fuzzing for netconf
* 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
- 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
* 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.
* 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
