a WORLD_SIZE > 12 makes the game crash

error: ```ArrayIndexOutOfBoundsException: <WORLD_SIZE>```
it happens in: 
```cell.pde```
```line #329```
in function: ```public void pushOut(Particle waste)```
```while(chosen == -1 || cells[y+dire[chosen][1]][x+dire[chosen][0]].type != 0){```

(i know I'm talking like a compiler error)