Started buildings undo system implementation

src/modules/stream/stream.cpp

@@ -337,6 +337,12 @@ void StreamWorld::run_command(const String &command, const Array &args)
 		bnode->set_global_transform(args[1]);
 		VariantWriter::write_to_string(buildings[id].xform, key);
 		buildings[id].key = key;
+	} else if (command == "buildings_checkpoint") {
+		/* TODO */
+	} else if (command == "buildings_undo") {
+		/* TODO */
+	} else if (command == "buildings_save") {
+		/* TODO */
 	} else
 		print_error("No command " + command);
 }

src/modules/stream/world_editor.cpp

@@ -120,6 +120,18 @@ void WorldEditor::editor_command(const String &command, const Array &args)
 		if (stream_world) {
 			stream_world->run_command(command, args);
 		}
+	} else if (command == "buildings_checkpoint") {
+		if (stream_world) {
+			stream_world->run_command(command, args);
+		}
+	} else if (command == "buildings_undo") {
+		if (stream_world) {
+			stream_world->run_command(command, args);
+		}
+	} else if (command == "buildings_save") {
+		if (stream_world) {
+			stream_world->run_command(command, args);
+		}
 	}
 }