多线程练习，功能能够实现时钟显示，闹钟，计时器，日期显示-Multi-threaded clock display, alarm clock, timer, date display

使用Timerd定时器制作数字时钟标签组件，显示当前日期和时间，每秒刷新。-Use Timerd timer making digital clock label component to display the current date and time, refreshed per second.