[Wonder-disc] Multicast change notification group

[Eugene K. <ve...@ma...>]

Hi! 

First of all, Mike, thanks for a MulticastSynchronizer! Great replacement
for a ERXChangeNotification.

But it seems like the value of er.extensions.multicastSynchronizer.group
property doesn't have an influence on sending and receiving datagram
packets. Instances with different groups were communicating with each other.
I was close to start thermonuclear war as you expected trying to figure out
the reason.
Attached patch fixes this problem for me. Check patch, please, as I'm new to
multicast sockets.

Thanks!

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Eugene Khablov
Media Agency "Design Maximum"