rsevents-extra 0.2.1

• A new public method Semaphore::count() has been added to query the available concurrency without affecting the state of the semaphore.
• Cross-core coherence and instruction ordering was previously insufficiently
  guaranteed; this is fixed in this release by directly using Ordering::Acquire and Ordering::Release instead of relying on the AutoResetEvent (access to which is sometimes elided as an optimization) to provide those guarantees.