Organize builtin into subdirectories

builtin/async/init.lua

@@ -0,0 +1,18 @@
+engine.log("info", "Initializing Asynchronous environment")
+
+local core = engine or minetest
+
+function core.job_processor(serialized_func, serialized_param)
+	local func = loadstring(serialized_func)
+	local param = core.deserialize(serialized_param)
+	local retval = nil
+
+	if type(func) == "function" then
+		retval = core.serialize(func(param))
+	else
+		core.log("error", "ASYNC WORKER: Unable to deserialize function")
+	end
+
+	return retval or core.serialize(nil)
+end
+