* 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
* Clarified semantics of main yang module:
* -y option to commands MUST specify filename
* CLICON_YANG_MODULE_MAIN MUST specify a module
* yang_parse() changed to take either filename or module name and revision.
* Removed clicon_dbspec_name[_set]().
* Use yang_main_module_name() instead.
* Replaced yang_spec_main with yang_spec_parse_module
* Added yang_spec_parse_file
* 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
statements and identifying them as extensions or not. However,
semantics for specific extensions must still be added.
* Renamed ytype_id and ytype_prefix to yarg_id and yarg_prefix, respectively
* Added cli_show_version()
for (eg cli_commitv). See clixon_cli_api.h for new names.
Use restconf format for internal xmldb keys. Eg /a/b=3,4
Changed example to use multiple cli callbacks
