More on PIVOT-861:  Simplify ListenerList<T> even further by using the
java.util.ArrayList<T> to implement it.  This eliminates the need for
the private NodeIterator class and simplifies all the methods to
(basically) defer to the implementing ArrayList.  Looking through the
Java source, it looks pretty much like ArrayList is doing exactly what
I was doing anyway, so there is no point in duplicating existing code.
The only (slight) drawbacks are the extra level of calls, and the fact
that ArrayList is slightly bigger (because of "modCount") than my
homegrown implementation.  But, now someone else can worry about any
bugs....


git-svn-id: https://svn.apache.org/repos/asf/pivot/branches/2.0.x@1448356 13f79535-47bb-0310-9956-ffa450edef68