(svn r106) New network core (by sign_de)

Features:
* network core is dynamicly loaded when needed (-n isn't needed anymore) 
  for easy switching between single and multiplayer. But commandline 
  shortcuts are still enabled:
   -n = autodetect network server
   -n [ip] = connect to the server
* udp now uses 2 different ports
  - you can run 1 server and serveral clients on one pc
  - the clients udp-socket gets unloaded when the
    network game starts
  - the servers udp-sockets remains online to allow the
    network gui to detect itself
* new gameinfo structure
  this struct is available for every online/lan game
* dynamic NetworkGameList

misc.c

@@ -542,6 +542,8 @@ void IncreaseDate()
 	/* yeah, increse day counter and call various daily loops */
 	_date++;
 
+	NetworkGameChangeDate(_date);
+
 	_vehicle_id_ctr_day = 0;
 
 	DisasterDailyLoop();