OK, maybe not actually remove because it is kept for fallback when the
new method isn't available.
The whole gametype parsing business had the same downsides as user agent
parsing on the web, hence I removed it while keeping behavior the same.
This allows servers to explicitly opt in or out of certain bug
workarounds and other client behavior. This increases the complexity of
different configurations that are available in the client (which is a
bad thing).
This system can easily be extended by independent authors without
collisions, something the old system with plain increasing integers did
not allow.
Do this by utilizing the previously unused message code `NETMSG_NULL`
which has a value of 0.
This works for engine and game messages, snapshot items and events.
