Integrated netsnmp agent and clixon event handling, made a workaround of fdset:s
used in the netsnmp API with sockets used in Clixon
Added a hardcoded MIB OID handler as subagent
Added libnetsnmpagent to autotools dependency check
New OE_SNMP error code
* Previous implementation did not handle nested if-feature expressions
* As part of fixing: [YANG if-feature does not support nested boolean expression](https://github.com/clicon/clixon/issues/341)
* Added new yacc/lex parser for if-feature-expr string
* Instead of using prefixes for augmented XML, assign the default namespace
Test: moved datastore format tests from test_cli to new test_datastore_format
Added support for list x y;
Uses a mechanism to parse as unknown XML body and post-parsing replace with list keys
Fixed example and test to work with new TEXT syntax
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 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)
* 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)`
* In the autocli and handcrafted CLI:s using `expand_dbvar()` the CLI expansion followed the leafrefs to the sources, ie the origin of the leafrefs
* Instead leafref expansion now only looks at the leafrefs
* Fixed: [Error message seen twice in some cases](https://github.com/clicon/clixon/issues/325)
* Extended `-l` command-line option to all clixon commands with a `none` option, eg `-l n` directs logging to `dev/null`
