Core/Session: proper client timeout detection (#1232)

* Core/Session: proper client timeout detection

- Properly detect client timeout when logged into a character after a configurable time (default 60s) has passed without the client sending any packets.
- Fixes issues with crashed clients leaving characters in the world for a very long time (default 15 minutes), as well as edge case exploits involving intentionally pausing client execution for some amount of time.

src/server/worldserver/worldserver.conf.dist

@@ -220,6 +220,15 @@ GridUnload = 1
 
 SocketTimeOutTime = 900000
 
+#
+#    SocketTimeOutTimeActive
+#        Description: Time (in milliseconds) after which an idle connection is dropped while
+#                     logged into the world.
+#                     The client sends keepalive packets every 30 seconds. Values <= 30s are not recommended.
+#        Default:     60000 - (1 minute)
+
+SocketTimeOutTimeActive = 60000
+
 #
 #    SessionAddDelay
 #        Description: Time (in microseconds) that a network thread will sleep after authentication