Merge pull request #231 from franz1981/not_final_mpsc_linked_atomic_q

Fixes #208: MpscLinkedAtomicQueue can be made not final

jctools-core/src/main/java/org/jctools/queues/atomic/MpscLinkedAtomicQueue.java

@@ -42,7 +42,7 @@
  * @param <E> the type of elements in this queue
  * @author nitsanw
  */
-public final class MpscLinkedAtomicQueue<E> extends BaseLinkedAtomicQueue<E> {
+public class MpscLinkedAtomicQueue<E> extends BaseLinkedAtomicQueue<E> {
 
     public MpscLinkedAtomicQueue() {
         LinkedQueueAtomicNode<E> node = newNode();