Player's own cells are removed from client if they go off screen

[Tom Burris]

I suppose more importantly, the server doesn't tell the client that the cell is theirs when it comes back on screen.
A side effect of this is that the client thinks the player has died if one or more of the player's cells are offscreen, and the cells on screen are killed. (Or if they all merge at once and you're really unlucky)

To reproduce:

• Get >450 mass
• Be one piece
• Eat a virus
• Have your small cells run away from your large one until the large one goes off screen
• Optionally: have your cells that are on screen, die

I'm not sure the best way to fix this problem, I'll continue to think about it.