Split the global cmd interpreter into 4 separate ones for specific uses (client conso...

Split the global cmd interpreter into 4 separate ones for specific uses (client console, server console, client commands received from server, server commands received from clients), this is intended to make clients more robust against malicious servers by restricting which commands make sense.

This also hides some network protocol implementation details from the console command interpreter, and makes the command list a lot shorter in dedicated servers.

Changed Cbuf_LockThreadMutex/Cbuf_UnlockThreadMutex to Cbuf_Lock/Cbuf_Unlock and they now use a spinlock internally.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12500 d7cf8633-e32d-0410-b094-e92efae38249