Add API function to invoke player respawn

closes #12272

src/script/lua_api/l_object.h

@@ -382,4 +382,7 @@ class ObjectRef : public ModApiBase {
 	
 	// get_lighting(self)
 	static int l_get_lighting(lua_State *L);
+
+	// respawn(self)
+	static int l_respawn(lua_State *L);
 };