#12 Event Blocker is not released when the client disconnected

[Tomoto Shimizu Washio]

[Problem]
When a client is disconnected, the Event Blockers (the
resources allocated inside the server to wait for specific
events to process waitForEvent etc.) for the client are
not be released. They remains until any matching
events appear.
This potentially results resource leaks if the matching
events never appeared, or unexpected disappearance of
events if the remaining Event Blocker was created by a
waitToRemoveEvent call.

[Suggested Fix]
When the server detected any network disconnection, it
releases Event Blockers related to the client.

[Workaround]
Nothing essential. Periodical rebooting of the server
may work.