remove y-coord from chunks

I removed the y-coord from chunks, I hope I didn't miss anything. Fixes #1344
Now you can slaughter me for removing too much. :P
Or will travis kill this commit first? :O
If I use false, then there weren't a chunk at ToLoad.m_ChunkX, ToLoad.m_ChunkZ, because it couldn't get loaded, I don't know if there is a check if a chunk is valid before it get send to a player, if not, the server will try to send a not existing chunk to the player.