Improve resource load cache

-Added a new method in Resource: reset_state , used for reloading the same resource from disk
-Added a new cache mode "replace" in ResourceLoader, which reuses existing loaded sub-resources but resets their data from disk (or replaces them if they chaged type)
-Because the correct sub-resource paths are always loaded now, this fixes bugs with subresource folding or subresource ordering when saving.

modules/visual_script/visual_script_nodes.cpp

@@ -303,6 +303,14 @@ VisualScriptNodeInstance *VisualScriptFunction::instance(VisualScriptInstance *p
 	return instance;
 }
 
+void VisualScriptFunction::reset_state() {
+	arguments.clear();
+	stack_size = 256;
+	stack_less = false;
+	sequenced = true;
+	rpc_mode = MultiplayerAPI::RPC_MODE_DISABLED;
+}
+
 VisualScriptFunction::VisualScriptFunction() {
 	stack_size = 256;
 	stack_less = false;
@@ -687,6 +695,13 @@ bool VisualScriptLists::is_sequenced() const {
 	return sequenced;
 }
 
+void VisualScriptLists::reset_state() {
+	inputports.clear();
+	outputports.clear();
+	sequenced = false;
+	flags = 0;
+}
+
 VisualScriptLists::VisualScriptLists() {
 	// initialize
 	sequenced = false;