* Yang 1.1 feature and if-feature according to RFC 7950 7.20.1 and 7.20.2.
* See https://github.com/clicon/clixon/issues/41
* Features are declared via CLICON_FEATURE in the configuration file.
* logical combination of features not implemented, eg if-feature "not foo or
* Identity without any identityref:s caused SEGV
* NOTE: Due to an error in the previous implementation, all XPATH calls on the form `x[a=str]` where `str` is a string (not a number or XML symbol), must be changed to: `x[a='str'] or x[a="str"]`
* This includes all calls to `xpath_vec, xpath_first`, etc.
* All calls to cli_copy_config in CLI spec files must replace 2nd argument from `x[%s=%s]` to `x[%s='%s']`
* The old API is stillenabled. To define the new, define XPATH_USE_NEW in include/clixon_custom.h and recompile
* Previous support did no validation of values.
* Validation of types and CLI expansion
* Example extended with inclusion of iana-if-type RFC 7224 interface identities
Added CLICON_XMLDB_FORMAT option. Default is "xml". If set to "json", XML database files uses JSON format.
Escape " in JSON names and strings and values
Optimized search performance for large lists by sorting and binary search.
