Add implementation based on kqueue

[npat-efault]

For BSD-derived systems that support it, a kqueue(2) based implementation would provide performance similar to the Linux epoll(7)-based one, without the limitations of select(2). It will also be very similar (trivial modifications) to the epoll(7)-based impl. Add one.

[vtolstov]

Im need this too =). Also may be windows implementation is very useful.