add 99 hours support

[JustusPan]

Currently the maximum time is 99 mins, which is too short for sketch training(or some other task). Could you please extend this tool to support dozens of hours?
你好，目前最大时间只能设定为99分钟，但是对于素描训练（或者其他事请）来说这个时间太少了。请问是否可以扩展功能以支持数十个小时的计时？

[xmha97]

+1