REL-1501: Modified BasicPropertyList to now use the Preferences class to...

... write values instead of using serialization. The serialization method was previously failing with ClassNotFoundExceptions upon deserialization due to not having access to the classes in question, and as per the specification of the REL task, based on the simplicity of the data being stored (boolean / int values exclusively), it was proposed that the values simply be written instead.
This method was used before to get a copy of the listeners with the lock held so that it could be iterated over without the lock.  Now it looks like we just iterate over a direct reference to the list without the lock held.  In a multithreaded context that means if someone adds or removes a listener while an event is being fired we would get a concurrent modification exception.  Probably this class is never used in a multithreaded context (but rather in the swing event thread) and this won't in fact happen.  If so we should verify that, remove the remaining synchronization and just state that it isn't thread safe.  It's probably easiest to just put something like this method back though.