Fixed More Bugs

Fixed the issue with integrated servers causing circular updates between
the combined server and client. We now check on the client side whether
the connection we're receiving data from is a memory connection (which
is presumably only used by integrated servers). If so, the client
ignores any incoming packets. We don't just disable update events
altogether because LAN games will require updating remote clients.

Also fixed a bug in PocketManager.unload() - we weren't setting isLoaded
to false after unloading everything and unregisterPockets() had to be
called before setting dimensionData to null.