Uses a gravity detector to move towards GRVT* and eat it. It can also follow other gravity sources.

It uses a special pstn mover design that won't break when it hits walls (no CRAY), and shouldn't ever break.

It's so good at following gravity that the last GRVT sometimes get stuck in the middle of the gravity detector!

EDIT: I added more cells that it can control, but if it runs into walls it will break. Remove them if you want.

*Make sure the tmp is lowered, or the wifi will break. I'm using tmp = 3. You should also set the life to 0 so the GRVT last forever.