Game Server Avatar Updates

The game server finally properly handles avatar update messages. Basically, all avatars are grouped into small areas. These areas align with the land block grid system used by the terrain renderer. As a player moves in and out of a particular land block (or entire land area), neighboring players are notified of this change. Avatars are thus dynamically loaded and unloaded on demand, based on where you currently are. Of course, to further optimize avatar rendering, distance and visibility tests are also incorporated by the client.