(cherry picked from commit 9d9f8fd8a337a1786efa0d348c89e05b26ce8571)

Each server in the server list requires a node. It's also MAXNETNODES-1 because
the first node is yourself.

(cherry picked from commit 1484f0484f6c22382b2cae955a93c01f83d54655)

-Added a timeout for game state downloading to prevent definitive join freezes in some cases. The timeout has a minimum value of "jointimeout" and gets higher as the game state grows in size
-If the server tries to kick a joiner who is downloading the game state, they will get a timeout instead, because a regular kick would only happen once the game state has been downloaded
-Added a timeout for player ticcmd packets, again to prevent freezes to happen in some cases
-File/game state downloading is now faster, the speed is controlled by the "downloadspeed" cvar, in packets per tic
-The reason is now properly shown when the server refuses connection
-Changed the default values of "nettimeout" to 10 seconds (previously 15) and "maxsend" to 4 MB (previously 1)
-Added a "noticedownload" cvar that displays a message in the server console when someone is downloading a file

(no actual SLOC changes)