Added new recursive minmax check for non-presence containers
This makes validation checks stricter, including check of incoming RPCs
Renamed xml_yang_check_list_unique_minmax() to xml_yang_minmax_recurse()
Fixed again: [YANG min-elements within non-presence container does not work](https://github.com/clicon/clixon/issues/355)
* Added new text syntax parsing and loading from CLI
* Unified text output functions to `xml2txt` and moved to clixon_text_syntax.[ch]
* The following are removed: `cli_xml2txt` and `xml2txt_cb`
* Text output format changed:
* Namespace/modulename added to top-level
* See [Support performant load_config_file(...) for TEXT format](https://github.com/clicon/clixon/issues/324)
* First hello is 1.0 EOM framing, then successing rpc is chunked framing
* See
* [Netconf framing](https://github.com/clicon/clixon/issues/50), and
* [Clixon does not switch to chunked framing after NETCONF 1.1 is negotiated](https://github.com/clicon/clixon/issues/314)
* C:
* Moved netconf framing code from netconf application to clixon lib
* Test:
* New expecteof_netconf and adjusted other expect scripts to handle NETCONF 1.1 framing