Fix StackOverflowExcpetion for large Lists

In large Environments the following StackOverflowException could occur:
<pre>
Running CacheEventBusCapacityTest
PublicationError{
	cause=java.lang.StackOverflowError
	message='Error during publication of message'
	listener=null
	listeningObject=null
	publishedObject=CacheEventBusCapacityTest$Event@99de5c}
java.lang.StackOverflowError
	at java.util.WeakHashMap.maskNull(WeakHashMap.java:328)
	at java.util.WeakHashMap.getEntry(WeakHashMap.java:492)
	at java.util.WeakHashMap.containsKey(WeakHashMap.java:484)
	at net.engio.mbassy.common.ConcurrentSet.remove(ConcurrentSet.java:68)
	at net.engio.mbassy.common.ConcurrentSet$1.remove(ConcurrentSet.java:115)
	at net.engio.mbassy.common.ConcurrentSet$1.hasNext(ConcurrentSet.java:93)
	at net.engio.mbassy.common.ConcurrentSet$1.hasNext(ConcurrentSet.java:94)
	at net.engio.mbassy.common.ConcurrentSet$1.hasNext(ConcurrentSet.java:94)
	at net.engio.mbassy.common.ConcurrentSet$1.hasNext(ConcurrentSet.java:94)
</pre>
I implemented the previous recursion as loop.