Overflow support?

[jitaogithub]

Hi there,

It seems from my reading of the code that this implementation doesn't support overflow. That is, say if a timeout of TIMEOUT_MAX + 1 is added before all the timeouts are expired, it will be added to wheel[0][0]. When the time is updated, instead of waiting till next round, this newly added timeout will be expired.

Please correct me if I got anything wrong, or if there is any specific reason why overflow support wasn't added. If not then I'm interested in adding it.