fix wrong date format

[Miaoyww]

#285

[Miaoyww]

by the way, at CommandTimerPlugin in 101, if the taskManager is null, it will throw a exception. so i made a check to avoid it

[Miaoyww]

while i finally noticed that if there is a timer that can not be loaded, it will disable the whole plugin. however, it is not excepted to happen.

i made a few try catch parts to avoid this problem.

[titivermeesch]

@Miaoyww Sorry for the long waiting here. Could you update the version again accordingly? I'll merge it after that