* Improved unknown handling
* Configure option `CLICON_YANG_DIR` is changed from a single directory to a path of directories
* Note CLIXON_DATADIR (=/usr/local/share/clixon) need to be in the list
* Except clixon-config module due to bug reported below
* Bug: Top-level Yang symbol cannot be called "config" in any imported yang file.
* datastore uses "config" as reserved keyword for storing any XML whoich collides with code for detecting Yang sanit
* Added urn:ietf:params:netconf:capability:yang-library:1.0
* Thanks SCadilhac for helping out, see https://github.com/clicon/clixon/issues/39
* uri_percent_encode() and xml_chardata_encode() changed to use stdarg parameters
* Changed Netconf hello to single capabilty urn:ietf:params:netconf:capability:yang-library:1.0 according to YANG 1.1 RFC7950 Sec 5.6.4.
* Set by option: CLICON_MODULE_LIBRARY_RFC7895 - enabled by default
* Option CLICON_MODULE_SET_ID is set and changed when modules change.