* NACM Data node READ access module support (RFC8341 3.4.5)

* Access control points added for `get` and `get-config` in addition to incoming rpc.
   * RFC 8341 Example A.2 implemented, see: [test/test_nacm_module.sh]
* Added `username` argument on `xmldb_put()` datastore function for NACM data-node write checks
* Added `xml_rootchild_node()` lib function as variant of `xml_rootchild()`

test/lib.sh

@@ -149,14 +149,17 @@ expectfn(){
   fi
 }
 
+# 
 expecteq(){
   ret=$1
   expect=$2
+#  echo "ret:$ret"
+#  echo "expect:$expect"
   if [ -z "$ret" -a -z "$expect" ]; then
       return
   fi
   if [[ "$ret" = "$expect" ]]; then
-      echo
+      echo 
   else
       err "$expect" "$ret"
   fi