* 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).
RCON upgrade with additional logging system improvements:
* Netconsole's can now log received messages in color, even when the RCON server has ANSI colors disabled; logs are fully composed locally.
* RCON server now also sends the log type over the wire, along with the (already existing) context.
* SDK logging code is now shared with the standalone netconsole application.
* Improved logging readability for the standalone netconsole application.
* Use game's CNetAdr RCON and socket creator.
* Add support for constructing host from [ip]:port format in the netconsole client.
* Pass 'netadr_t' parameter by reference to 'CSocketCreator::OnSocketAccepted'.
Implemented StringSplit() (split string with a delimiter, and stop splitting after either the last delimiter has been reached, or nMax, so when nMax is 2, then 'SET mat_sky_color 255 255 0 255' gets split into: "SET" "mat_sky_color" "255 255 0 255").
Netconsole now sends ConVar's/ConCommands and values separately with use of StringSplit.
ConVar now uses internal ChangeStringValue (this runs the callback).
