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)`
* 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)
