tree data OPTIMIZE diff and lyd_insert_node()

Function lyd_insert_node() has new options that ignore the ordering of
data nodes. This is used in lyd_diff_add() because the diff as such
does not need to be sorted.
diff --git a/src/validation.c b/src/validation.c
index 1faf3f1..ecba13d 100644
--- a/src/validation.c
+++ b/src/validation.c
@@ -2047,7 +2047,7 @@
     op_parent = lyd_parent(op_subtree);
 
     lyd_unlink(op_subtree);
-    lyd_insert_node(tree_parent, &tree_sibling, op_subtree, 0);
+    lyd_insert_node(tree_parent, &tree_sibling, op_subtree, LYD_INSERT_NODE_DEFAULT);
     if (!dep_tree) {
         dep_tree = tree_sibling;
     }
@@ -2096,7 +2096,7 @@
         lyd_insert_before_node(op_sibling_after, op_subtree);
         lyd_insert_hash(op_subtree);
     } else if (op_parent) {
-        lyd_insert_node(op_parent, NULL, op_subtree, 0);
+        lyd_insert_node(op_parent, NULL, op_subtree, LYD_INSERT_NODE_DEFAULT);
     }
 
     ly_set_erase(&node_when, NULL);