Enchancement realtime hash wheel timer

This commit implements a realtime, core-occupying hash wheel timer.

It is not to be used in single-core environments, since it will take control
of a core and busy-spin until it's cancelled.

Instead of thread.sleep(), a busy-spin is used here.



We can provide an imprecise, non-realtime HashWheel timer that will not occupy the core,
and sleep instead, given the fact that there would be no way for it to be even 10 milliseconds
precise. It will be at best 100ms precise, but even that can't be guaranteed in highly-concurrent
environment.

To be honest, an initial implementation was looking more like that one. I've opted out for sleeps
since hoped that there will be a way for parking a thread / sleeping to be precise enough.