schema compile CHANGE store default values as in lyd_value structure

Use the data trees's structure to store the default values even in
the compiled schema tree. It is necessary for default value validation
and useful for instanciating default nodes in data trees.
diff --git a/src/printer_xml.c b/src/printer_xml.c
index 813d032..8d2dd01 100644
--- a/src/printer_xml.c
+++ b/src/printer_xml.c
@@ -334,6 +334,20 @@
 static LY_ERR xml_print_node(struct xmlpr_ctx *ctx, const struct lyd_node *node);
 
 /**
+ * @brief XML mapping of YANG modules to prefixes in values.
+ *
+ * Implementation of ly_clb_get_prefix
+ */
+static const char *
+xml_print_get_prefix(const struct lys_module *mod, void *private)
+{
+    struct ly_set *ns_list = (struct ly_set*)private;
+
+    ly_set_add(ns_list, (void*)mod, 0);
+    return mod->prefix;
+}
+
+/**
  * @brief Print XML element representing lyd_node_term.
  *
  * @param[in] ctx XML printer context.
@@ -344,18 +358,28 @@
 xml_print_term(struct xmlpr_ctx *ctx, const struct lyd_node_term *node)
 {
     LY_CHECK_RET(xml_print_node_open(ctx, (struct lyd_node *)node));
+    struct ly_set ns_list = {0};
+    unsigned int u;
+    int dynamic;
+    const char *value = node->value.realtype->plugin->print(&node->value, LYD_XML, xml_print_get_prefix, &ns_list, &dynamic);
 
-    if (((struct lysc_node_leaf*)node->schema)->type->plugin->flags & LY_TYPE_FLAG_PREFIXES) {
-        /* TODO get prefixes from the value and print namespaces */
+    /* print namespaces connected with the values's prefixes */
+    for (u = 0; u < ns_list.count; ++u) {
+        const struct lys_module *mod = (const struct lys_module*)ns_list.objs[u];
+        ly_print(ctx->out, "%sxmlns:%s=\"%s\"", u ? " " : "", mod->prefix, mod->ns);
     }
+    ly_set_erase(&ns_list, NULL);
 
-    if (!node->value.canonized || !node->value.canonized[0]) {
+    if (!value || !value[0]) {
         ly_print(ctx->out, "/>%s", LEVEL ? "\n" : "");
     } else {
         ly_print(ctx->out, ">");
-        lyxml_dump_text(ctx->out, node->value.canonized, 0);
+        lyxml_dump_text(ctx->out, value, 0);
         ly_print(ctx->out, "</%s>%s", node->schema->name, LEVEL ? "\n" : "");
     }
+    if (dynamic) {
+        free((void*)value);
+    }
 
     return LY_SUCCESS;
 }