* More precise Yang validation and better error messages

* For Example, adding bad-, missing-, or unknown-element error messages, etc instead of operation-failed
* Removed delete-config support for candidate db since it is not supported in RFC6241.
* Switched the order of `error-type` and `error-tag` in all netconf and restconf error messages to comply to RFC order.
* Added example_rpc RPC to example backend
* Renamed xml_namespace[_set]() to xml_prefix[_set]()
* Some restconf error messages contained "rpc-reply" or "rpc-error" which have now been removed.
* Netconf/Restconf RPC extra input arguments are ignored (https://github.com/clicon/clixon/issues/47)

test/test_cli.sh

@@ -13,8 +13,10 @@ APPNAME=example
 . ./lib.sh
 cfg=$dir/conf_yang.xml
 
+# Use yang in example
+
 cat <<EOF > $cfg
-<config xmlns="http://clicon.org">
+<config xmlns="urn:example:clixon">
   <CLICON_CONFIGFILE>$cfg</CLICON_CONFIGFILE>
   <CLICON_YANG_DIR>/usr/local/share/$APPNAME/yang</CLICON_YANG_DIR>
   <CLICON_YANG_DIR>/usr/local/share/clixon</CLICON_YANG_DIR>
@@ -115,7 +117,7 @@ expectfn "$clixon_cli -1 -f $cfg -l o debug level 0" 0 "^$"
 new "cli rpc"
 expectfn "$clixon_cli -1 -f $cfg -l o rpc ipv4" 0 "<address-family>ipv4</address-family>" "<next-hop-list>2.3.4.5</next-hop-list>"
 
-if [ $BE -ne 0 ]; then
+if [ $BE -eq 0 ]; then
     exit # BE
 fi