* Decoding and encoding is done into a single buffer, from raw buffers to avoid extraneous copies.
* Added base class holding all core logic for encoding, decoding, receiving and processing of the RCON protocol. This code was initially identical between all implementations of RCON, deduplicating this avoids bugs.
* Added more sophisticated error handling, stop right away when decoding for example fails.
* Added ability to have more than one active authenticated net console on the server. Controlled by cvar 'sv_rcon_maxconnections' (default 1).
* Max packet size for accepted, but not authenticated sockets is now controled by cvar 'sv_rcon_maxpacketsize' (default 1024).
* Fixed 'connect' socket bug preventing connection to IPv4 addresses, by making the method used by the listen socket and connect socket configurator shared (dual stack was disabled on connect, but not on listen).
* Removed extraneous member from the 'CSocketCreator' class, this member was a copy of the 'netadr_t' input, but nothing ever was done with it.
