Variable Reactor.OpenOptions.timerGranularity

Base granularity of the reactor's timer.

struct Reactor.OpenOptions
{
  // ...
  core.time.Duration timerGranularity = Duration(10000L);
  // ...
}

Any scheduled task is scheduled at no better accuracy than timerGranularity. In addition to the fact that a timer task may be delayed. As such, with a 1ms granularity, a task scheduled for 1.5ms from now is the same as a task scheduled for 2ms from now, which may run 3ms from now.